On the night of the “Rocket Richard Riot” in 1955, the legendary Cartier Dagger is stolen from its protective glass case in Montreal’s imposing Sun Life Building. The dagger, which once belonged to the explorer Jacques Cartier, has been on loan to Clarence Campbell, the controversial president of the NHL. Many believe the dagger gives whoever possesses it mystical powers; as a result, its journey through history is as spectacular as it is bloodstained. On the night of its theft, a man is found murdered in a nearby park, with a dagger wound to his heart. Detective Armand Touton quickly recognizes the dead man as his friend and informer Roger Clement, a local hoodlum. But who murdered him, and why?

Thirteen years later, Pierre Elliott Trudeau is prime minister and the separatist movement is gaining momentum in Quebec. The case is still unsolved. Touton asks Émile Cinq-Mars, a young constable, to continue the investigation, warning him to proceed with caution. Wanting to impress Touton, Cinq-Mars works quickly to wrap his mind around this puzzling case.