While entertaining her lover one weekend, a woman's marriage is threatened by the sudden appearance of her evil step-brother. Beyond using her home to hide from the police after his recent heist, he also blackmails her in to a horrendous weekend filled with debauchery and violence. After her ordeal she is anything but bored.

In the course of a violent hold-up at Deauville station, several innocent bystanders are shot dead. The victims include a politician, Robert Andréani, and three members of the same family. Devastated by the death of his wife, daughter and mother, Martin Modot resolves that their killers will be brought to justice. When the police fail to make any progress in their investigation, he decides to take matters into his own hands, with the support of a neo-fascist vigilante organization.