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.