Based on the popular whodunit novels of Elizabeth George, this BBC series partners two New Scotland Yard investigators -- Thomas Lynley (Nathaniel Parker) and Barbara Havers (Sharon Small) -- whose contrasting backgrounds make them an unlikely pair. But put them together, and there's no mystery they can't solve. In "A Traitor to Memory," a woman's tragic past leads the detectives to an obvious suspect with motives that just don't add up.