Pars vite et reviens tard

In Paris, a mysterious stranger predicts the return of the plague, and Detective Jean-Baptiste Adamsberg (José Garcia) investigates the strange occurrences when citizens find 4s painted on their apartment doors with "clt" - a symbol that leads him to meet retired historian Hervé Decambrais (Michel Serrault). As more victims are found, Adamsberg discovers they all worked for a pharmaceutical company in the Congo, and he must unravel the connection between them. The investigation reveals a complex web of motives and deceit, ultimately leading to the shocking revelation that Marie Gillain's character is the real murderer.