Ben Dafoe, emergency-room doctor and part-time crime-scene consultant for the Seattle P.D., is haunted by addiction. Two years before, a cocaine habit claimed the life of his identical twin, Aaron. Now Ben walks onto the scene of a savage stabbing to learn that the victim, Emily Kenmore, is his former fiancÔee, another loved one who fell prey to addiction. In Emily's bedroom is a streak of blood on the wall that belongs to the killer. When the DNA from that sample matches Ben's blood, he becomes the prime suspect. Convinced that his identical twin is alive and somehow involved in Emily's death, Ben frantically hunts for Aaron while trying to evade the authorities. But someone is desperate to thwart him. While Ben struggles to solve a tragic mystery from his past to clear his name in a crime of the present, he learns that sometimes blood lies.