Forensic psychiatrist Jo Beckett is called to the scene of an aircraft inbound from London to help deal with a passenger who is behaving erratically. Jo realizes her patient's addled mind may hold the key to preventing something terrible from happening in her beloved San Francisco. In order to prevent it, she will have to get deeper into the life of a patient than she ever has before, hoping the truth emerges from the fog of his mind in time to save her city--and herself.