A municipal worker's strike combined with Frankfurt's hottest summer in 150 years brings infected rats out onto the streets.

A crime writer on a train to Berlin shares her compartment with a mysterious man who claims to be a cannibal. Initially intrigued, she tries to humorously dismiss his claim while her imagination sparks a new novel featuring Detective Rosa Roth, who investigates a similar case. As the journey progresses, the writer’s confidence fades, replaced by fear and mistrust. The man’s behaviour becomes more unsettling, especially after a young girl reports inappropriate comments from him. In the dining car, he claims to have eaten a fellow passenger and reveals his tools are nearby. Despite her fear, the writer is drawn to learn more about his methods, blurring the lines between her novel and reality. Ultimately, her fantasy merges with reality, leading to dire consequences.