Newly promoted homicide detective Mike Sweeney struggles to keep his family together as they try to come to terms with the anguish left behind by a serial killer. He also develops an intense bond with a brilliant but deeply troubled forensic psychiatrist named Pen Verrity, who works in his department.

Mike Sweeney's new task force investigates the brutal murder of two young boys along the 401 highway corridor, while one of their own officers struggles to bury a dangerous secret. Meanwhile, Audrey and Sadie embark on a new chapter of their lives, and Mike must push himself beyond his limits to overcome a sudden tragedy that may tear his family apart forever.