Based on the 1954 novel L'Horloger d'Everton by Georges Simenon, it tells the story of a widowed father who first discovers how little he knows about his teenage son, who kills a man and with his girl goes on the run, but then decides that whatever their faults he will stand by the pair.

[3] Respected professionally and socially, the widowed watchmaker Michel Descombes lives peacefully over his shop in Lyons with his teenage son Bernard, who works in a factory.

One morning when his son has not come home, which is not unusual, police arrive and take Michel to see their inspector, who gradually breaks the news that the boy has killed a man and fled with a girl called Liliane.

Arrested, the young people are flown back to Lyon for trial and Michel hires a lawyer, who has his own ideas on defence.

The inspector also thinks the crime was not premeditated but the court is not convinced, giving Bernard 20 years for murder and Liliane 5 for abetting.