When the existence of a strain of
plague (vaguely identified as
pneumonic) is revealed at the US mission at the
International Health Organization in
Geneva, three terrorists seek to blow up the US mission. Two of them are shot, one mortally, by security personnel, but one escapes. The surviving terrorist is hospitalized and quarantined and identified as Swedish. Elena Stradner and US military intelligence Colonel Stephen Mackenzie argue over the nature of the strain, which Stradner suspects is a
biological weapon but which Colonel Mackenzie claims was in the process of being destroyed. The third terrorist, Eklund, escapes and stows away on a train travelling from Geneva to
Stockholm. Stradner believes that the train should be stopped so that the terrorist can be removed and quarantined, but Col. Mackenzie is concerned that all of the passengers on the train might be infected. Mackenzie insists on rerouting the train to a disused railway line which goes to a former
Nazi concentration camp in Janov,
Poland, where the passengers will be quarantined. However, the line crosses a dangerously unsound
steel arch bridge known as the Kasundruv Bridge or the "Cassandra Crossing", out of use since 1948. Mackenzie understands that the bridge might collapse as the train passes over it. The presence of the infected terrorist, and the rerouting of the train, precipitates the second conflict, among passengers on the train who include Jonathan Chamberlain, a famous
neurologist; his ex-wife Jennifer Rispoli Chamberlain, a writer; a former inmate of Janov and
Holocaust survivor Herman Kaplan; and Nicole Dressler, the wife of a German arms dealer. She is embroiled in an affair with her young companion Robby Navarro. Navarro is a
heroin trafficker being pursued by
Interpol agent Haley, who is travelling undercover as a priest. Mackenzie informs Chamberlain of the presence of Eklund, who is found hiding in the baggage car next to a caged
basset hound, but attempts to remove him via helicopter are unsuccessful. Just before the train enters a tunnel, the dog infected with Eklund's plague is transferred to the helicopter and taken back to the IHO lab. Chamberlain is also told that the plague has a 60% mortality rate. Mackenzie, however, informs passengers that police have received reports of anarchist bombs placed along the rail line, and that the train will be rerouted to
Nuremberg. There the train is sealed with an enclosed oxygen system and a
US Army medical team is placed aboard, with the now-deceased terrorist being placed in a
hermetically sealed coffin. Armed guards with
shoot-to-kill orders from Mackenzie also board the train, who wound Kaplan when he tries to escape. Chamberlain learns of the risk of the Cassandra Crossing. Chamberlain also begins to suspect the disease is not as serious as originally thought: few of the passengers have become infected and even fewer have actually died. He radios Mackenzie suggesting the infected portion of the train be uncoupled and isolated, but Mackenzie, acting under orders, has no intention of stopping the train: if, as expected, the Cassandra Crossing collapses, it will neatly cover the fact that the American military has been harbouring germ warfare agents in a neutral country. Chamberlain and Haley form a group of passengers to overcome the guards and seize control of the train before it reaches the doomed bridge. At the lab, Dr. Stradner tests and monitors the ill dog, which spontaneously recovers, but Mackenzie is unimpressed and refuses to alter his plan. Navarro is killed by the guards as he attempts to reach the engine from the outside. Haley is killed during a firefight while protecting a girl passenger. Kaplan learns of the plot to blow up the club car's
bottled gas supply and expose the coupler. He sacrifices himself by setting off the explosion with a cigarette lighter. Chamberlain manages to separate the rear half of the train, hoping that with less weight the front half will cross safely. But the bridge collapses, killing everyone aboard the front half. Max, the train's conductor, applies the manual brakes and stops the remaining cars just before reaching the downed bridge. The survivors soon evacuate the remaining cars and head off on foot, no longer under guard or quarantine. In Geneva, both Stradner and Mackenzie depart: she keeps hope of survivors while he feels quiet guilt over the whole affair. After they leave, Major Stack informs Mackenzie's superior that both the colonel and the doctor are under surveillance. ==Cast==