A high-speed train breaks down on a viaduct in the middle of a storm. Among the passengers, six teenagers, total strangers, suddenly fall prey to strange phenomena: hallucinations of ghostly apparitions and ghostly voices... Terrified at first, they become violent. One of them assaults the ticket inspector; another threatens passengers with a knife. Are these acts of vandalism perpetrated by an organised gang, as the press claims, or inexplicable events that defy logic and understanding? What mysterious link connects these young people? And why this train, on this particular night?