Castle and Beckett investigate what seems to be an intelligence operative’s assassination; Beckett’s relationship with Demming strains her relationship with Castle.

A robbery-homicide prompts Beckett to invite Demming to assist on a case, giving Castle a ringside seat to their budding romance. When it becomes clear that the two men have very different ideas about how to proceed, the investigation becomes an unspoken competition for Beckett’s attention, one in which each man races to solve the case, as Beckett referees between her two admirers.

A high profile chef is found frozen to death in the kitchen of a hot New York restaurant. Complications ensue when Castle and the restaurant owner, an old high school girlfriend of Beckett’s, share an attraction. Meanwhile, Beckett’s relationship with Det. Demming continues to grow.

Investigating the murder of a thief, Castle and Beckett are surprised to learn that Esposito has a personal connection to the suspected killer. Another surprise is in line for Castle when Beckett hits it off with the handsome Robbery detective assigned to the case, Tom Demming. Now this romantic triangle must work together to solve the case.

When talk show host Bobby Mann (Tom Bergeron) mysteriously dies, Castle is convinced that there was foul play; a guest on Bobby Mann’s show (Kelly Carlson) seduces Castle.

The investigation into the shocking death of a museum curator, crushed by a falling gargoyle, takes a bizarre turn when Castle and Beckett learn that he isn’t the first member of a recent archeological expedition to die. It turns out there was a legend inscribed over the burial chamber the team unearthed warning that “all who gaze upon the face of the mummy are doomed.” Was the curator just the latest victim of “The Mummy’s...

In the second part of the story begun in “Tick, Tick, Tick,” the serial killer remains at large and is taunting Castle, Beckett and Jordan Shaw to catch him

Federal Agent Jordan Shaw, an insightful and accomplished Federal investigator teams up with Castle & Beckett to hunt down a cunning and elusive serial killer.

When a half-naked woman is found covered in caramel sauce and hanging by bondage cuffs in a public park, Castle and Beckett’s investigation takes them into New York’s underground world of sexual domination. Naturally the case serves as sexy fodder for their already charged relationship banter.

A beloved former major league baseball player is found dead after a goodwill trip to Cuba. The investigation, which includes running into Joe Torre, leads the detectives into New York’s Cuban community to solve the murder. Meanwhile, Alexis’ genealogy project forces Castle to consider the identity of his unknown father.

Castle and Beckett investigate the murder of a dead man found in a family’s house that just returned from vacations. Meanwhile, Castle is elected as one of New York’s 10 most eligible bachelors.

Castle and Beckett investigate the death of an Irish mobster, but while on the case they uncover what may be an international drug smuggling operation, as well as the killer may be involved in the murder of Beckett’s mother.

Castle and Beckett are called to a wedding to investigate the murder of a bridesmaid. Castle realizes that the wedding is from a former girlfriend Kyra. Everyone’s feelings are compromised, since Kyra has doubts about who she is marrying, Castle’s feelings may not be as objective in the case and Beckett picks up the connection between them, making her a little jealous and have poor judgement.

An amnesiac is the key witness to an art dealer’s murder, but can’t recall what happened. Castle and Beckett’s probe hits another snag when they discover a bullet is missing from the crime scene.

A man’s body is discovered in an apartment building’s garbage chute, and two women surface to identify the deceased—his wife and his fiancée. Castle and Beckett’s investigation uncovers the man’s complex double life. DB Woodside guest stars

The murder of an Assistant District Attorney thrusts Castle and Beckett into the world of ex-cons and escorts. But when Castle’s desire to help a vulnerable call girl endangers the case, Beckett is forced to decide between honoring promises and putting a killer behind bars. Matters are complicated even further when Castle’s daughter shares a potentially explosive secret with Beckett instead of her father

After a bike messenger, carrying a package with content that is able to free a wrongly convicted man from pison, is brutally murdered, Castle and Beckett need to investigate the case. But they are surprised to find out that the tragic death is linked to another murder case previously investigated by Captain Montgomery. Now, in order to solve the new murder, Castle and Beckett must dig deep and discover all the secrets of a prominent New...

When an up-and-coming rock star’s dead body is found staged in a scene straight out of her hit music video, Castle and Beckett delve into the world of obsessed fans, sleazy managers and jealous band members. But it’s only when Alexis uncovers the true meaning behind the lyrics of the final song that clues to the killer’s identity begin to surface

As Halloween approaches, Castle and Beckett are called to a graveyard where the body of a young man sporting vampire fangs has been discovered with a wooden stake driven through his heart. Their investigation takes them deep into the heart of New York’s underground vampire fetish community, where they learn that the motive for the victim’s murder may be hiding within the pages of the graphic novel he was writing before his death.

Castle has a new book agent, Paula Haas, but she talks with him when he has gotten an opportunity that may change his career. The downside is that taking the opportunity would mean the end of his relationship with Beckett. Meanwhile, an unidentified woman is found dead in a manhole.