Writer Nick Castle is called into help the police department after two murders occur that are strikingly similar to the plot of his book.

When a body of a young woman is found inside the dryer at a laundry room, Castle and Beckett uncover that the young woman worked as a nanny in the upscale building. Meanwhile, as Castle works on his Nikki Heat novel series he watches Beckett’s actions as she works the murder case.

The son of a once wealthy family is found dead in Central Park. As Castle and Beckett are working on the investigation his friends are trying to stop them. Castle isn't sure he can trust Martha to be left alone while he chaperones Alexis' class on a field trip to Washington DC.

The investigation behind a body found wrapped in a rug on the sidewalk leads Castle and Beckett deep inside the world of New York City politics. The partners discover a world of expensive escorts, arrogant tycoons, corrupt investigators, and the effects of betrayal.

A frozen woman is found tangled in steel bars at a construction site, leading Beckett and Castle to connect it to a cold case. As the two uncover facts about the victim’s past, Beckett must face hard memories of her own, giving Castle insight and material for his novel.

Beckett and Castle are drawn into the world of Vodun, a mystical religion which Castle studied for a previous book, due to a ritualistic killing. Elsewhere, Castle prepares for a possible return of Alexis’ mother.

Beckett must leave her comfort zone and enter into Castle’s zone of paparazzi’s portraying his date in hopes of causing the high-end home invasions and thefts, one which ended in a murder. Meanwhile, Castle asks the assistance of dangerous jewel thief who once made threats to his life.

A woman was found murdered inside a transient hotel in a bathtub full of motor oil as Castle and Beckett investigate. After uncovering the dark past of the woman, they decide they’ll need to seek the help of a crime journalist who may know more about this woman than he is telling. Meanwhile, Beckett uses her best poker face as she squares off against Castle, with both money and pride at stake.

Beckett assists in a missing-child investigation only to discover that her ex-boyfriend is the lead FBI agent, for whom she still has feelings for. Castle complicates the situation more when he insists on joining the probe.

Castle and Beckett investigate the murder of a plastic surgeon who disappeared and was found a week later dead in the front seat of his vehicle parked curbside. While delving into the world of surgery obsessed patients and secret operations, Castle has a fatherly experience as Alexis attends her first prom. And as Castle looks back into Beckett’s past, he discovers information which could stop their relationship forever.