Montreal, today: On the day before Christmas, Judith Harper, a renowned psychologist, is brutally murdered. At the same time, Nathan Lawson, a respected lawyer, disappears after panicking and burying documents in a cemetery. Shortly thereafter, a homeless man jumps from a skyscraper. In the homeless man's coat are the wallets of Harper and Lawson. When Sergeant Detective Victor Lessard, who is himself a troubled soul, and his partner Jacinthe Taillon begin their investigation, they receive a disturbing recording featuring the voice of Lee Harvey Oswald, the man who once shot J.F. Kennedy and is now speaking to them from beyond the grave. Lessard and Taillon are faced with a case that leads them into the darkest depths of both the human soul and American history.