A late-night train departs from London, carrying a modest number of passengers through the countryside. Among them is Joe, an agitated guard who is unhappy with his job and feels undervalued. The journey takes a dark turn when the train suddenly grinds to a halt in a remote, forested area. Initially thinking it's an ordinary mechanical failure, Joe and the passengers soon discover that they're not alone. A bloodthirsty creature attacks the train, forcing everyone on board to confront their worst fears and band together to survive.

As the passengers fortify their positions and attempt to fend off the relentless creature, interpersonal tensions rise. Fear and desperation reveal hidden facets of each character, compelling them to make life-and-death decisions. Joe emerges as an unlikely leader, trying to keep the group focused despite fraying nerves and rising panic. As they work together to find a way out, the bond among the survivors strengthens, but so does the peril they face. Each attempt to fight back or escape brings them closer to understanding the true nature of the danger they're up against, culminating in a nightmarish ordeal for all involved.