The body of a young woman has been discovered in Bellahouston Park, the second in a matter of months. It's clear to Detective Superintenent William Lorimer of Police Scotland that they have a repeat killer on their hands, who is sure to strike again. Lucky for DSI Lorimer that his wife, Maggie, is miles away from potential danger, touring Scotland to promote her first book. Faced with strangers at every event, Maggie doesn't notice the quiet, non-descript man sitting in the back row.