A bomb explodes in a busy Montreal street. A mob lawyer blown apart, an innocent child murdered. Watching and powerless to provent it is Montreal's most illustrious policeman - Emile Cinq-Mars. Then the corpse of a young man, Artinian, is found hung from a rafter with the inscription M-5 dangling round his neck. M-5, March 5th, a calling card in English. When Cinq-Mars discovers that Artinian had infiltrated the mob for a foreign agent he drawn is back to the bombing. Linking the two crimes, the detective finds himself in the midst of the Canadian mob's move to control all crime in the country, their ambition fuelled by a new ally whose ruthlessness knows no limits -the Russian mafia, and in particular an enigmatic crime boss known as the Czar. Whom the Czar cannot buy off he kills but even he cannot risk murdering the famous Emile Cinq-Mars. However, another mole, Julia Murdick, is infiltrating the Czar's organisation, another young idealist risking his life to fight the mob. Can she help Cinq-Mars catch the Czar? Can he save her from almost certain death when her cover is blown - just as Artinian's was?