The attack begins in the Houston Ship Channel, in the cargo hold of the Belize-flagged, Singapore-owned container ship Ocean Princess. The vessel is eight hundred feet long. It is stacked from stem to stern with forty-foot-long steel boxes and looks oddly top-heavy. On international manifests its cargo is listed as “toys and electrical components.” But that’s not all it is carrying. Inside one of the containers, each of which can hold thirty tons of cargo, is a stockpile of terrorist-planted explosives that makes Timothy McVeigh’s Oklahoma City bomb look like a firecracker.

As the ship steams north and west toward the heart of Houston, there are no signs that anything is wrong. The U.S. Coast Guard boards the ship and performs a routine inspection, interviewing the captain and crew but opening no containers. U.S. Customs and Border Protection, which uses an x-ray machine to inspect some 10 to 12 percent of containers entering the port, sees nothing suspicious in this shipment and elects not to screen it.

But as the ship approaches the giant Shell Oil refinery in Deer Park, the Coast Guard’s port commander receives a panicked call from the Department of Justice’s Counterterrorism Section in Washington. It’s bad news: The Ocean Princess is probably carrying a bomb. The Coast Guard scrambles into action, but it is already too late. Before the cutters can reach the vessel, an immense blast rocks the channel and surrounding areas.

As Homeland Security officials will later discover, the bomb consists mostly of Soviet-era anti-ship mines, originally loaded onto the Ocean Princess in Trieste, Italy, by an obscure but well-organized group of Algerian and Moroccan terrorists. The explosives are triggered by a device known as a GPS detonator, which sets them off as soon as a certain longitude-latitude coordinate is reached. In this case, the coordinates were for Shell’s refinery. Today the terrorists are lucky: The bomb goes off just as the container ship is also passing a seven-hundred-foot liquefied petroleum gas (LPG) tanker. The blast rips into the side of the tanker, causing yet another large explosion, which in turn both ignites gasoline and crude-oil storage tanks at Shell and causes the tanks’ walls to rupture, sending a river of fire out into the refinery and reaching the far more dangerous pressurized pentane storage tanks. A little more than 11 million gallons of pentane are released, some of which burns and some of which evaporates and forms a vapor cloud, which then explodes with enormous force, leveling buildings and structures in the immediate vicinity. By the time another compartment on the LPG tanker is breached, sending a new fireball into the sky, more than two hundred people are dead. The container ship is half-submerged, still burning and resting on the bottom of the fifty-foot-deep channel. But all this, as Houstonians and the rest of the world will soon learn, is merely prelude. What happens next is scarcely imaginable.

CHARLES DICKENS once described Pittsburgh, Pennsylvania, as “hell with the lid off.” His reference was to that city’s vast landscape of smoke-belching steel mills, but the metaphor also works for something much closer to home: the grotesquely magnificent stretch of refineries, petrochemical and other plants, mills, docks, silos, wharves, and warehouses that rise along the banks of the malodorous waterway known as the Houston Ship Channel. Over its full fifty-mile track—from near downtown Houston to Bolivar Roads, on the Gulf of Mexico—the channel houses three hundred plants and is one of the largest concentrations of heavy industry on earth, producing nearly half of the nation’s supply of gasoline and half of its petrochemicals. It comprises the largest refinery in the world (Exxon Mobil, in Baytown) and the sixth-largest seaport. Viewed from the tollway bridge on Houston’s east side, the upper channel can seem both frightening and, in its own dark, industrial Gothic way, weirdly beautiful. On certain days the whole brutish apparatus seems to hiss into action, spewing fire and emitting long, gorgeously looping plumes of cottony white steam that coil around its steel tanks and spires and rise hundreds of feet into the sky. Dickens, who chronicled England’s industrial revolution, would have felt right at home.

But as the above hypothetical attack suggests, the channel is more than just a spectacular industrial engine. It is also a prime terrorist target. That’s because it is both ground zero for the nation’s petrochemical industry and home to unfathomably large quantities of the deadliest, most combustible, disease-causing, lung-exploding, chromosome-annihilating, and metal-dissolving substances known to man. The sheer toxicity of it all, in fact, is one of the main reasons the channel zone evolved as it did: Part of the idea was to confine all of these poison-laden refineries and chemical plants and ships filled with anhydrous ammonia to their own noxious neighborhoods, generally away from homes and schools and offices. You don’t want to put storage tanks next to nursery schools if they have the potential for igniting and leveling every building within a half-mile radius. Chemical plants can kill people at long range, but it is still a bad idea to put them next to residential subdivisions. Back in the twenties and thirties, when industries began to locate along the channel en masse, this must have seemed like a sound idea. In the year 2004, when terrorist attacks are daily events and people fly planes into the World Trade Center to make a political statement, this sort of unarmored industrial concentration is like having a giant target painted on us with a sign, in Arabic, that reads “Attack here.”

As most Houston residents can tell you, the Ship Channel has long been considered one of the top strategic targets in the United States. Russian missiles were (and perhaps are) aimed at it. A single well-placed strike would cripple a significant portion of our national economy. Along with the rest of the city, the channel was put on a Code Orange terrorist alert during Super Bowl week in January. Two months later the FBI announced another alert—again Code Orange—specifically for the Ship Channel. It is unclear what the feds thought was going to happen. Beyond their disconcertingly vague warnings, they plainly aren’t ever going to share their real concerns with us.

Which more or less leaves it to us to imagine what the effects of a terrorist attack might be. The notion that the Ship Channel is an enormous bomb waiting to be detonated is an oft-repeated truism. Everyone agrees that it is, but that tells you nothing about what happens when the bomb actually goes off. As we roll on and off of the now-familiar Code Orange alerts—only one notch back from Code Red, which means, presumably, that cargo planes loaded with TNT are already winging toward Disney World—it might be helpful to know exactly what it is that we are supposed to be afraid of. By that I do not mean minor bits of terrorism such as strapping one hundred pounds of C-4 explosives to a petroleum barge and sinking it in the channel or running a truck packed with Semtex explosives into a tank farm. Those are mere annoyances. I mean a full-scale, worst-case scenario of the sort the Homeland Security folks are modeling and simulating and staying up late worrying about, an attack that would have as deep and abiding an effect on the public as the horrors of 9/11. If we are supposed to believe these alerts, it seems only fair to ask: How would it happen in the Houston Ship Channel?

TO UNDERSTAND HOW a terrorist strike might affect this vast tangle of smoke and steel, it helps to look at the horrific industrial accidents that already happen there with surprising regularity. Things are always blowing up or burning out of control or leaking in the channel—much as they would be likely to in a terrorist attack. (Since 1955 the place has even had its own private fire brigade, with two hundred pieces of heavy equipment—Channel Industries Mutual Aid, or CIMA—that does nothing but put out the fires and fix the accidents.)

The worst of all the channel disasters was the 1947 explosion of the French freighter S.S. Grandcamp at a dock in Texas City. The ship was loaded with ammonium nitrate, the same stuff McVeigh used to craft his truck bomb in Oklahoma City 48 years later. A fire on the ship caused a blast that leveled docks, warehouses, and a chemical plant; damaged or destroyed one thousand residences or buildings; and killed 578 people. It remains the worst industrial accident in American history and led to sweeping changes in chemical manufacturing and storage.

Still, major accidents continue to happen. In 1979 the tanker Chevron Hawaii exploded at the docks of Shell Oil’s Deer Park refinery, killing 3 people and touching off a cascade of explosions and fires in storage tanks that engulfed Shell’s docks and the nearby channel. The blast tore the ship in half, caused two nearby gasoline and crude-oil barges to explode, and filled the channel with a twenty-foot wall of burning crude oil. In 1987 a crane operator at Marathon Oil’s Texas City refinery dropped an industrial heater on a storage tank, causing the leak of 30,000 pounds of deadly hydrogen fluoride, which formed a gas cloud. Thousands were evacuated from Texas City, and 800 people were treated for breathing disorders and skin problems. The worst of the recent accidents took place in 1989, when an explosion ripped through a petrochemical plant in Pasadena owned by the Phillips Petroleum Company. The blast—equivalent to igniting 20,000 pounds of TNT—started in an ethylene reactor and created an orange fireball that was described by one witness as looking like the detonation of an atomic bomb. The explosion was heard 25 miles away, broke windows 3 miles away, leveled most structures on four hundred acres of property, and tossed debris for miles. It killed 23 people, wounded 130, and left a grim wreckage of twisted steel and concrete.

To see just how hazardous the products of the channel’s plants are, you have to read the companies’ own worst-case scenarios. Under law, each plant must make such a report—known as a risk management plan (RMP)—and file it with the Environmental Protection Agency. This information is public but is considered to be so sensitive that my request to the EPA in Houston for the documents brought an immediate return phone call from the Department of Justice’s Counterterrorism Section in Washington, asking who I was and what I wanted. In order to view the RMPs for channel plants, I had to go to the U.S. Marshal’s office at the federal courthouse in Houston, where I was escorted to a private room and watched by a guard for two hours while I read the material. I was allowed to take notes but not to remove or copy any of the information. After I left, the documents were shredded.

The information in the RMPs is sobering, in part because the premise is that these are accidents, not deliberate attacks. Attacks would cause much more damage. A sampling reveals the plants’ astonishing ability to kill or maim human beings. In their toll on human life, the worst substances by far are so-called toxics, like chlorine, ammonia, and hydrogen fluoride, as opposed to the flammables, like pentane and butane. Take, for example, Oxy Vinyls’ Battleground plant, which makes chlorine and caustic soda. According to its RMP, the daily production of liquid chlorine is collected in seven 650-ton storage tanks, and its worst-case scenario “assumes 1.3 million pounds of liquid chlorine [one full tank] would be released and evaporated in a ten-minute period.” The chlorine gas cloud would travel 25 miles before falling below the EPA’s toxic threshold of three parts per million and would affect 1.8 million people. How many died or became acutely ill would depend largely on wind speed and direction and on what time of day the accident occurred. Fatalities are not addressed in the RMP. But based on worst-case scenarios run by other organizations, they could easily be in the tens of thousands.

In Pasadena the Crown Central Petroleum refinery’s worst case involves a “catastrophic failure of the hydrofluoric acid storage drum resulting in the release of 50,000 pounds of hydrogen fluoride gas over a ten-minute period.” The distance to what the EPA calls the “toxic end point” is 9.3 miles. The spill would affect 650,000 people. BP Amoco’s worst case in Pasadena involves the “liquid spill and vaporization” of 4,440 pounds of iron pentacarbonyl. Toxic end point: 3.9 miles. People affected: 84,881.

While it is harder to kill large numbers of people in the channel area with explosions alone, the worst-case scenarios from some of the refineries still indicate a serious threat to local communities: Shell Oil’s giant Deer Park refinery lists a pentane “vapor cloud explosion” as its worst case. The explosion “could affect areas up to 1.8 miles away” and up to 5,532 people, according to its RMP. The nearby Lyondell-Citgo refinery also lists pentane as its worst case. Toxic end point: 1.68 miles. People affected: 20,100.

Though the RMPs make no mention of terrorism, they do offer clues as to how much worse an attack would be than the hypothetical accidents they describe. A concerted terrorist assault might, for example, release the entire contents of all seven of Oxy Vinyls’ chlorine tanks, instead of just one. Chlorine is very nasty stuff. In 1915 it was the German army’s choice for the first deadly chemical attack in history, which killed 5,000 Allied troops in Belgium. A number of other widely used chemicals—including anhydrous ammonia, hydrogen fluoride, and methyl isocyanate—are also fatal to humans. A leak of the latter from a Union Carbide plant in Bhopal, India, in 1984 killed 3,800 people in a single night and injured more than 500,000. (Many more would die later.) It was the single largest industrial accident in history and a perfect working model for chemical terrorism. Chemical weapons cost a great deal of money to develop and are difficult to deploy. Chemical factories, on the other hand, are plentiful, full of lethal compounds and relatively easy to blow up or sabotage. Before 9/11, many people in the chemical industry believed that a worst-case scenario was so unlikely that it wasn’t worth planning for. Clearly that is no longer true.

FROM THE DECK of a Coast Guard patrol boat on the murky, dredged-out sliver of bayou that is the upper Ship Channel—the 23 miles of densely packed industry containing 89 large plants from the Turning Basin (where ships turn around), near downtown Houston, to Exxon Mobil’s refinery in Baytown—it is easy to see why the place is so vulnerable. There are giant steel containment vessels everywhere, many of the 10-million-gallon variety. They are often bunched tightly together. At one refinery, I saw some thirty of them within a quarter mile. Huge liquid chlorine and LPG spheroids also dot the landscape, as do the ubiquitous black, ninety-ton rail tanker cars and tanker trucks, many bearing signs like “Anhydrous Ammonia—Inhalation Hazard!” The biggest tanks of all are the six-hundred- to eight-hundred-foot ships filled with such volatile substances as gasoline, crude oil, ethylene, and LPG.

And as you pass by this seemingly endless expanse of industry, it is clear that no matter what sorts of security improvements might be made, the channel still has one big, basic problem. As a port that accommodates 6,400 ships and 150,000 barges each year and countless railcars and trucks, is directly connected to more than 287,000 jobs in Texas, and handles 177.6 million tons of goods yearly, many from foreign-flagged ships, the Port of Houston is by definition open and porous. You cannot lock it down. The Ship Channel is all about commerce, not security. There is far too much coming and going to mount anything like a foolproof defense against a terrorist attack.

Not that people are not trying. In the wake of 9/11, vast changes have taken place in the way the channel and its industries are guarded. The Coast Guard, which is in charge of inspecting all shipping, has a sophisticated vessel-tracking system that uses color coding to distinguish ships with hazardous cargoes from those without. Port security is also buttressed by new laws that took effect on July 1 requiring full security plans for all plants and vessels, detailed advance notice of all incoming ships, information about their crews and cargoes, and provisions for ship escorts and armed sea marshals for the most dangerous shipments. But in fact the Coast Guard has only twelve ships in the channel and four large cutters off the coast and a relatively small number of personnel to handle the incoming traffic. Nationally the Guard has about 39,000 people, fewer than the New York Police Department. It simply does not have the ability to screen every ship. Only one in five vessels is boarded, and most of those are searched only cursorily. Though U.S. Customs has significantly increased its ability to use x-ray machines to screen cargo, only one ship in ten has its contents x-rayed. This is national policy, and it is clearly improving, especially in addressing the problems of U.S. ports. But no one thinks ports are safe, and critics of the current administration have argued that if the U.S. had spent the Iraq war and occupation budget on things like expanding U.S. Customs and the Coast Guard, ports would be much safer today than they are.

Nor do individual plants have anything like airtight security, in spite of significant new investments in personnel, security fencing, prisonlike watchtowers, concrete barricades, cameras, and detectors. A month after 9/11, with the nation on high alert, infiltrators in frogman suits gained access to Sterling Chemicals in Texas City. In December 2003, while the nation was on a Code Orange alert, Houston Chronicle reporter Steve McVicker, a photographer, and a security consultant were able to easily breach security at a number of chemical plants along the upper channel. McVicker wrote that he and his team, in their SUV, were “allowed unimpeded access to ships, docks, warehouses, heavy equipment, and bridge supports.” At one point they drove “within a few feet of a crew unloading a cargo ship without being challenged.”

But the greatest single security threat exists in the form of the 21,000 containers that arrive each day in U.S. ports. There are 11 million containers in use around the world; they are each loaded and unloaded ten times per year. The problem with containers, as drug dealers and smugglers have long understood, is that they are opaque, easy to disguise or mislabel, and run a relatively small chance of being opened or screened by radar. Examples abound of how easy it is to subvert the system. In October 2001 a stowaway was discovered in Italy in a container bound for Toronto. When arrested, he was found with a global satellite phone, a cell phone, a laptop, an airliner mechanic’s certificate, and security passes for airports in Canada, Thailand, and Egypt. It was not clear what he was planning to do. The container had been loaded in Port Said, Egypt, onto a German-owned, British-chartered, Antigua-and-Barbuda-flagged ship. It looked exactly like the 2.5 million other containers handled by the Italian port that year. The stowaway was discovered only because a crew member happened to see him trying to widen the air vents in his container.

There are many such stories showing how easily subverted our shipping systems are. When local emergency committees model terrorist attacks, they often use containers as the means of assault, and there is no one who believes that the present methods of security and screening are even close to being terrorist-proof. “There is virtually no security for what is the primary system to transport global trade,” said U.S. Customs commissioner Robert Bonner in August 2002. “If terrorists used a sea container to conceal a weapon of mass destruction and detonated it on arrival at a port, the impact on the global economy would be devastating.” Coming from the Customs commissioner, that is a frightening statement. While the system has been trimmed and tightened since he made it, there is still a long way to go before anyone can be sure that ships carrying bombs are not steaming up to loading docks in the heart of America’s largest cities.

Which is why I began my hypothetical attack aboard a container ship. But most experts agree that, in an industrial area where explosions are not uncommon, a terrorist strike would likely involve much more than that. “Mischief is not what they are after,” says Peter Ulrich, of RMS Associates, a company that models disasters and terrorist attacks for the insurance industry. “They want to make an impact. We react most strongly to massive destruction and people killed. Sabotaging the New York Stock Exchange would be a pain in the butt, but it would not directly affect most people’s lives. The attack on the World Trade Center was a horrifying, large-scale event that most people can relate to.”

With that in mind, I have constructed a more ambitious attack, one with multiple phases designed to take advantage of the Ship Channel’s many vulnerabilities and to accomplish everything the World Trade Center attack did and more. There is no single authority on this: The event is constructed from histories of industrial accidents, the worst-case scenarios in the RMPs, and five terrorist war games invented by the National Emergency Response and Rescue Training Center, the Houston Local Emergency Planning Committee, RMS Associates, and Booz Allen Hamilton consultants in partnership with the Conference Board business group. All of this information is public; indeed, it is deliberately so. Right now cities and counties across the country run terrorist-attack scenarios similar to the one that follows on a routine basis.

IN THE MINUTES after the detonation of the container in the hold of the Ocean Princess, the community responds as it usually does in an emergency. Fire, rescue, and EMS teams are dispatched; local TV news crews hustle to the scene. But they will soon learn that the awesome blast is merely a sideshow, not the main event. EMS teams within a mile of the blast quickly discover that the air is full not only of smoke and fire and choking fumes from oil, gas, and various petrochemicals but also of radioactive contamination. That is because the conventional explosives also contained three radioactive isotopes: cobalt 60, cesium 137, and plutonium 238. This is known as a “dirty bomb,” or an RDD—a radiological dispersal device. Materials for such a bomb are all readily obtainable from hospitals, research facilities, industrial and construction sites, and from such common commercial tools as machines that irradiate food products. Its purpose is to scatter low-level radiation over as wide an area as possible. The idea is less to kill—which such low levels can rarely do—than to sow panic.

Which is exactly what it does. News that radiation sensors are going off all over east Houston creates mass hysteria. Soon one million Houstonians are on the move, clogging highways and streets. News of the dirty bomb, coupled with the earlier intelligence that there might be others, effectively shuts down all commerce at all U.S. ports. Nothing moves, in or out. Homeland Security orders every container—on trucks, railcars, or ships—either x-rayed or opened and searched. In other cities there are huge traffic jams as people flee from imagined danger.

In spite of the spreading panic, fire, public health, and EMS crews fight their way bravely to the scene. CIMA is possibly the premier fire-fighting agency in the world. It has fixed leaks and put out all sorts of chemical and oil fires. Even such a large explosion, which now includes sunken ships blocking the channel, is quickly handled. Dirty bombs make this all vastly more complicated. Still, CIMA, the Coast Guard, EMS, and other emergency teams have rehearsed this. They have a plan. They know what sort of protective gear to wear and how to decontaminate victims. They know that the main harm from a dirty bomb comes from the blast itself, not the radiation. But while the enormous fireballs were rising in the channel, a series of explosions in a nearby chlorine plant went initially unnoticed. Members of a terrorist sleeper cell have managed to detonate three 250-ton chlorine storage tanks, causing the tank walls to collapse and almost all of the liquid chlorine to escape within ten minutes. A dense, faintly yellowish gas cloud, denser than one thousand parts per million, kills all of the nearby workers at the plant and moves off on a five-knot northerly breeze toward the city of Deer Park, population 29,000. Everyone in the near vicinity of the plant dies.

Deer Park—which only minutes before has discovered that it is the victim of a radiological attack—now becomes a scene of utter terror and devastation. Chlorine is extremely toxic to humans. It causes violent laryngeal spasms. When it reacts with liquids in the body, it creates hydrochloric acid, which produces an acute burning sensation. As it is inhaled, it spreads hydrochloric acid throughout the upper respiratory system. It also causes pulmonary edema, a condition in which you, in effect, drown in the fluids in your own lungs. Thousands nearest the plant suffocate and die in their homes; workers on the lower floors of buildings die.

The cloud reaches the center of the city of Deer Park, still at a highly toxic density of more than two hundred parts per million. Everywhere, people are convulsing with pulmonary edema. And now the emergency workers are truly overwhelmed, as are hospitals and ERs. Hundreds of thousands of people are being evacuated. Medical teams are treating many with severe breathing problems, and there are nowhere near enough ventilators to handle the worst cases. The cloud is dispersing but still covers ten square miles and is defoliating trees all over south and east Houston. News of the chemical attack, coming on top of news of the radiological attack, has created an exodus of people that has virtually stopped all traffic in Houston. People are leaving their cars and trying to walk out of the city, suffering from nasal or tracheal inflammation and streaming eyes as they go.

Several hours later, winds pick up and disperse most of the chlorine gas, but the damage remains. Rescue workers all across the city treat people with acute chlorine burns and radiation poisoning. By the next morning, the grim totals are being flashed around the world in news broadcasts: More than 10,000 people are dead—some 500 from the bomb blasts and the rest from chlorine poisoning. Thirty-thousand are injured and jamming the makeshift hospitals and ERs that have sprung up all over Harris County. The only good news is that Harris County emergency teams, trained extensively to respond to these sorts of attacks, have been remarkably well organized. Though almost every system is overrun and all ERs overwhelmed, medical teams have managed to treat or decontaminate enormous numbers of victims. This is a direct result of the many rehearsals emergency teams have done since 9/11 for precisely this sort of attack.

In economic terms, the cost will be astronomical. The Dow drops precipitously; gasoline prices skyrocket. Corporate earnings plunge, just as they did after 9/11. In a war game conducted earlier this year in which several dirty bombs were discovered in containers but none actually detonated, Booz Allen Hamilton and the Conference Board estimated the total damages at $58 billion—just from a 22-day paralysis of our ports and border crossings. The costs in this case would be many multiples of that, the strain on insurers far greater. It will take several weeks to open the channel to shipping. It will take months to decontaminate areas in the cities of Houston, Deer Park, La Porte, and Pasadena, both for chlorine and radioactive particles from the bomb.

As for what steps we might take as a nation after this attack or what new demons it might unleash, who knows? For now it is enough to understand that, while such a terrorist assault on the American heartland is wholly fictional, it is also, beyond a doubt, entirely plausible.

With reporting by Kate Getty.

Big Bang Theory

The Houston Ship Channel has seen many disasters, including the explosion of the Chevron Hawaii in 1979. A well-planned terrorist attack would likely have the same goals as did the depredations of 9/11: widespread destruction of property and human life and the sowing of mass fear, panic, and confusion. To those ends, the Houston Ship Channel offers terrorists what war planners call “a target-rich environment.” Here’s how an attack might go down: 1) A huge container ship entering the upper Houston Ship Channel is blown up, and the impact sets off a cascade of violent explosions that include a liquefied petroleum gas tanker and a nearby oil tank farm. Authorities soon discover that the first explosion was also a “dirty bomb,” producing radioactive dust and particles that contaminate the areas near the channel. 2) Workers at a nearby chemical plant who are secretly part of a terrorist sleeper cell detonate three 250-ton chlorine storage tanks. 3) Propelled by a northerly wind, the chlorine plume drifts south, killing thousands.