When the body of an infamous mobster who disappeared in the 1970s is found, Castle and Beckett find one remaining witness. But since he still believes it's the '70s, they must act like his delusion is real in order to find their killer.
When a Wall Street Trader is murdered the investigation is complicated when they find out the victim was a confidential informant for a US Attorney who happens to be Capt. Victoria Gates' estranged sister on Castle.
When a woman confesses to murder, she tells the detectives details only the killer would know, but when someone else confesses with the same knowledge Castle and Beckett realize this case is more mysterious than they originally thought.