Ben Dafoe, a young emergency-room doctor and part-time crime-scene consultant for the Seattle Police Department, is haunted by addiction. Two years earlier, a cocaine and crystal-meth habit claimed the life of his identical twin, Aaron. Now Ben walks onto the scene of a savage stabbing to find that the victim is his former fiancee, Emily Kenmore-another loved one who fell prey to drugs. Part of the carnage in Emily's bedroom is a single streak of blood caked on the wall.

When the DNA from that sample matches Ben's, he becomes the prime suspect.

Convinced his identical twin is...