Kate has settled into her new life running the Avondale Puzzle Museum in Granville, New Hampshire, and the locals have begun to accept her presence. Until a serial killer from Boston starts making his way north up I-93. At the same time a former partner of Police Chief Brandon’s shows up with information about the killer. The killer who has just struck Granville. The killer who puts the Police Chief out of commission. The serial killer who leaves a puzzle at each crime scene. The serial killer who, it seems, is focused on Kate.