When a famous psychic is murdered, Beckett and Castle search for her killer while also carrying on a spirited debate on the existence of extrasensory abilities. Evidence mounts on both sides, especially when a letter arrives from the victim, penned the day she was killed and predicting her own death -- or was it written by a clever killer, hoping to throw off the investigation?

Castle and Beckett look into the murder of a young mathematician gunned down with a 200-year-old bullet, sparking some wild theories by Castle about a time-travelling killer. When their investigation uncovers a tricked-out DeLorean and a suspect in Victorian clothing, is it possible Castle's crazy idea has some validity? This winding tale twists through the towers of Wall Street and into the world of a secret steampunk society that embraces the romance and simplicity of the past, while coupling it with the hope and promise of the future.