Description
In 1906, Professor Sir Alexander Saxton, a renowned British anthropologist, is returning to Europe by the Trans-Siberian Express from Shanghai to Moscow. With him is a crate containing the frozen remains of a primitive humanoid creature that he discovered in a cave in Manchuria. He hopes it is a missing link in human evolution. Doctor Wells, Saxton\'s friendly rival and Geological Society colleague, is also on board but travelling separately. Before the train departs Shanghai, a thief is found dead on the platform. His eyes are completely white, without irises or pupils, and a bystander initially mistakes him for a blind man. The Polish Count Marion Petrovski and his wife, Countess Irina, are also waiting to board the train with their spiritual advisor, an Eastern Orthodox monk named Father Pujardov, who proclaims the contents of the crate to be evil. Saxton furiously dismisses this as superstition. Saxton\'s eagerness to keep his scientific find secret arouses the suspicion of Wells, who bribes a porter to investigate the crate. The porter is killed by the defrosted humanoid within. It then escapes the crate by picking the lock.
The humanoid finds more victims as it roams the moving train. Each is found with the same opaque, white eyes. Autopsies suggest that the brains of the victims are being drained of memories and knowledge. One of the victims is a spy sent to find out the secrets behind Count Petrovski, who has invented a type of steel. When the humanoid is gunned down by police Inspector Mirov, the threat seems to have been eliminated. Saxton and Wells discover that external images are retained by a liquid found inside the corpses\' eyeballs, which reveal a prehistoric Earth and a planetary view as seen from space. They deduce that the real threat is somehow a formless extraterrestrial that inhabited the body of the humanoid and now resides inside the inspector. Pujardov, sensing the greater presence within the inspector and believing it to be that of Satan, renounces his faith, pledging allegiance to the entity.
News of the murders is wired to the Russian authorities. An intimidating, xenophobic and power-crazed Cossack officer, Captain Kazan, boards with a handful of his men. Kazan believes the train is transporting rebels; he is only convinced of the alien\'s existence when Saxton switches off the lights and Mirov\'s eyes glow, revealing him to be the alien\'s host. It has absorbed the memories of Wells\' assistant, the train driver, and others aboard, and now seeks the Polish count\'s metallurgical knowledge in order to build a vessel to escape Earth. Kazan stabs Mirov with his shashka and then shoots him. With Mirov dying, the alien transfers itself to the deranged Pujardov.
The passengers flee to the brake van while Pujardov murders Kazan, his men, and the count, draining all of their memories. Saxton rescues the countess and holds Pujardov at gunpoint. Saxton, having discovered that bright light prevents the alien from draining minds or transferring to another body, forces Pujardov into a brightly lit area. The alien Pujardov explains that it is a collective form of energy from another galaxy. Trapped on Earth in the distant past after being left behind in an accident, it survived for millions of years in the bodies of protozoa, fish, and other animals. It cannot live outside a living being longer than a few moments. The alien begs to be spared, tempting Saxton with its advanced knowledge of technology and cures for diseases. When Saxton refuses the bargain, the alien resurrects the count\'s corpse and attacks him with it.
Saxton and the countess flee, but the alien resurrects all of its victims as zombies. Fighting their way through the train, Saxton and the countess eventually reach the van where the other survivors have taken refuge. Saxton and Wells work desperately to uncouple the van from the rest of the train. Kazan\'s superiors sends a telegram to a dispatch station ahead, instructing them to destroy the train by sending it down a siding overlooking a gorge. Speculating that war has broken out, the station staff switch the points.
The alien takes control of the train as it enters the siding. Saxton and Wells finally manage to separate the van. The alien tries to find the brakes but fails to slow down the train. It crashes through the buffer stop, plunging down the deep cliff, and is destroyed after it hits the bottom. The van rolls precariously to the end of the track before stopping, inches away from the cliff. Saxton, Wells, the countess and the survivors gaze over the ravine as an inferno engulfs the train and its unearthly inhabitant.
