On a luxurious train traveling through Europe, a group of passengers from various nationalities becomes embroiled in a mysterious murder. Among them is the famous Belgian detective Hercule Poirot, who has just completed a case in the East and is heading home. During a stormy night, the millionaire Samuel Ratchett is found dead in his compartment, stabbed multiple times. The situation complicates when the train is trapped by a landslide, leaving the passengers isolated.
Poirot, always elegant and methodical, decides to take matters into his own hands. As he interrogates the iconic characters on board—a high-society lady, a nurse, a businessman, among others—dark secrets and unexpected connections begin to emerge. Each of them seems to have a perfect alibi, but also hidden motives that could have driven someone to commit the crime. With his keen observation and deductive skills, Poirot embarks on a deadly game of intrigue, facing lies, betrayals, and surprising twists.
In a thrilling climax, the detective discovers that nothing is as it seems, and that the passengers share a dark connection with the victim. The truth will come to light, but not without challenging sudden loyalties and moral decisions that will change the lives of everyone on board.