All Detective Mason Callahan wanted was a fishing trip to unwind, but instead he found the body of his boss Denny Schefte near their remote cabin with his throat slit and face covered by a mask. Mason is determined to catch the sadist who killed his friend. When the FBI learns of the mask left at the scene, they realize they have a serial killer targeting cops on their hands. They assign the case to Special Agent Ava McLane, who is engaged to Mason, despite her own recent trauma. As Ava delves into the disturbing case, the killer may be closer than she expects.