In the series finale, lives are endangered unexpectedly when Castle and Beckett prepare to take on LokSat.
A psychiatric inmate escapes and drops dead in Castle's PI office, and the investigation that follows has Castle surmising the Antichrist could be involved.
A movie star who transitioned to theater work is killed, so Castle and Becket go behind the scenes to investigate what was going on in the actor's life.
A city inspector cheats death twice when he survives poisoning and electrocution attempts on his life, and a curious Castle and Beckett grow determined to solve this mysterious case.
Hayley helps an old pal, but this favor gets her in trouble, linking her to a murder and a cyber-terror attack. She then needs help herself, so Castle and Beckett attempt to clear her name.
Castle and Beckett embark on a search for Aladdin's lamp after a man linked to smuggling Turkish antiques is killed.
One of Esposito's old cases is reexamined by Castle and Beckett because of a clue left at a crime scene involving an armored-car driver's murder.
The team head to the NYPD Academy for an investigation involving a murdered recruit. Meanwhile, Castle grapples with a decision with far-reaching ramifications for himself and Beckett.
Castle returns to Los Angeles in search of info about the missing time related to his abduction, and while he's there, the Greatest Detective Society reaches out to him and asks for his assistance in solving a murder.
A student learning to speak English is killed and his classmates keep mum when questioned by police, so Castle goes undercover to gain info on the victim by enrolling in the class as a French Canadian immigrant.
Castle gets abducted and must solve puzzles and mind games with a group of strangers. Meanwhile, Beckett and her colleagues race against the clock to find Castle and capture a killer.
A Russian diplomat's son is killed, leading Castle and Beckett to learn about international crime and foreign politics as Castle is tasked with keeping a Russian security officer busy.
Castle takes the stand as the key witness in a murder trial, but then new info emerges late in the case, leading him and Beckett to rush to prevent a miscarriage of justice.
A body is found in a theater where Martha is working, so Castle and Beckett investigate and are surprised to learn how cutthroat Acappella singers can be.
An entertainer on a cruise ship is killed, and Castle and Beckett investigate while trapped on the ship with the murderer.
A seductive con man is killed, and the investigation has Castle and Beckett questioning New York City's upper crust. Meanwhile, Castle has a surprise in store for his and Beckett's one-year anniversary as husband and wife.
Det. Slaughter returns seeking Castle's help in a robbery case. However, Slaughter becomes a suspect when the heist case turns into a murder case, and Castle's unsure about whether his pal is innocent or guilty.
An art thief steals a rare painting and kills the person transporting it, so Castle and Beckett team up with the key witness in order to find the culprit.
A hermit-like author idolized by Castle is killed, and Castle resolves to solve the murder.
Castle goes undercover as a professor after a college fraternity student is killed in a grisly manner. During the investigation, he and Beckett unearth some sinister secrets the university wants to keep suppressed.
In the conclusion of the eighth-season opener, Beckett's disappearance is examined from her angle as she fights to stay alive and uncover who wants to see her demise.
Since passing her Captain's exam and the offer to run for State Senate, Beckett and Castle are adjusting to her career change. A call from a mysterious stranger sets off an unpredictable chain of events.