Author Richard Castle joins NYC Detective Kate Beckett to help solve the case of a serial killer who is reenacting murders from Castle's novels; Castle becomes very intrigued with the murders and continues to shadow Beckett, much to her chagrin.

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.

When a teenaged boy whose family has recently fallen on hard times is found dead in a boat in Central Park, Castle and Beckett must piece together the mystery behind the boy's final moments. Meanwhile, Castle mulls over leaving Martha home while he chaperones Alexis' trip to Washington, D.C.

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.

Castle and Beckett investigate the murder of a women found frozen and tangled in steel bars at a construction site. The case leads them to look into an old case and also has Beckett thinking about some memories of her past.

After discovering a young woman's body stuffed awkwardly into a jewelry safe, Beckett and Castle investigate numerous cases involving murders and home invasion jewel heists.

Castle and Beckett investigate the murder of a woman found drowned in motor oil in a motel bathtub. They seek the help of a true crime journalist who might have a connection to the victim.

When a two-year-old girl is discovered missing from her home, Beckett is called in to assist with the investigation only to discover that the FBI agent in charge is, in fact, her ex-boyfriend. The two of them try to put aside their unresolved feelings as they race to find the girl, but when Castle inserts himself into the investigation, competition quickly heats up for Beckett’s attention.

Castle and Beckett investigate the murder of a missing plastic surgeon who is found dead in the front seat of his car after a week of being parked curbside. As they delve into the twisted world of surgery obsessed patients and secret operations, Castle experiences a fatherly rite of passage as Alexis attends her first prom. And while looking into Beckett’s past, he unearths information that could end his relationship with her forever.