Detective Sergeant Surprenant, a veteran of major crimes in Montreal who took refuge in the Islands, investigates with the help of his colleague Geneviève Savoie and inexperienced police officers, even giving up his vacation to solve this sad story. However, he must deal with the arrogant chief inspector Sébastien Gingras, dispatched from Quebec and with whom he has disagreements.
Anne Fortier is a criminal psychologist who works with the investigators of SAS (Anti-Sociopathic Service), a fictional police division specializing in crimes involving mental illnesses. Although their crimes include a shoe thief and a pyromaniac, most of the cases given a lot of time on the series are murders, often serial killings. While solving these cases Fortier and her colleagues must wrestle with her own murky past and psychological issues.