Beckett and her team burst into an apartment on a murderer's trail, only to be surprised when they find Castle, who they hadn't seen or heard from in months, standing over the dead woman's body holding a gun. Beckett has no choice but to arrest Castle until he proves he is innocent.
A famous medium is found dead, stuffed in a sofa-bed, by her daughter. Castle seems convinced that the medium predicted her own murder, but Beckett thinks she's a fake and a charlatan. Who's right? Meanwhile, Castle's mother is dealing with traumatic events in her own life.
With the latest case of a murdered bail bondsman, Beckett discovers that Castle's wild imagination and theories may be on the mark. Beckett's ex-partner makes a surprise arrival and Castle is forced to watch the two reminisce and engage in a little romance.
When a County Hospital doctor's body is discovered in someone else's casket, Castle and Beckett dive into the complex relationships in the hospital and the doctor's life to uncover the killer. Meanwhile, Castle's relationship with his ex-wife is strained over a pair of concert tickets.
When a woman's dead body shows signs of an old killer's handy work, Castle and Beckett discover that the Triple Killer, a murderer who vanished four years prior, may have returned. Meanwhile, Alexis has a secret admirer.
When a prominent astrophysicist is found dead in her car of explosive decompression, Castle is led to theorize her death was the result of an alien abduction, particularly when a government agent tries to stop the investigation.
When Castle's novel "Heat Wave" is turned into a movie, actress Natalie Rhodes, shows up at Beckett's invitation to better understand the character she's going to play. Meanwhile, the threesome investigate the murder of a high-class matchmaker.
Old wounds are reopened when the retired lead detective on Beckett’s mother’s homicide case contacts her with new information, but then is gunned down right in front of Beckett before he can tell her what he knows. The investigation into his death leads back to a decades-old conspiracy that may hold the answer to who was behind Beckett’s mother murder and why. With the stakes and emotions running high, Castle and Beckett take their partnership to the next level.
Castle and Becket Investigate the murder of a New York Taxi driver who was shot and stripped of his car parts. However, as they search for his killer, they are lead to a storage with trace amounts of nuclear substances and evidence that a bomb and terrorism is at play. Castle on the other hand sense that they have been set up and searches for the truth and ends up getting Beckett and himself caught in a very icy situation.
A murder has been committed on the set of “Temptation Lane,” one of New York’s longest running soap operas. Sarah Cutler, the head writer on the soap, has been killed with a fire axe. Castle and Beckett quickly discover that the behind the scenes drama at “Temptation Lane” is just as scandalous as the fictitious storylines, and just about everyone would kill to get ahead. Ultimately, Castle’s unique skill set as a writer leads to a discovery about the killer and the secret he or she would do anything to protect.
During the high-profile trial of a murdered socialite, a juror suddenly tumbles out of the jury box -- dead! When Castle & Beckett learn the juror was poisoned, their investigation soon uncovers that this seemingly innocent juror may not have been so innocent after all.
Castle & Beckett work the case of a man found dead inside a pizza oven, but it turns out not to be someone associated with the restaurant – it was a reporter. Was his story, “The Pizza Wars,” enough to get him killed, or was it something much deeper than that?
When Beckett travels to L.A. against orders, with Castle, to solve the murder of her ex-partner, Castle questions her motives. Meanwhile, they get to meet the actors who will be portraying Esposito and Ryan in the film adaptation of Castle's first novel Heat Wave.
Castle and Beckett are called to investigate when a contestant in a beauty pageant is found strangled and every suspect has a motive to commit murder, including jealous fellow contestants, the pageant's sponsor, and the show's host.
Kate Beckett’s investigation into her mother’s death is reactivated when Hal Lockwood – a professional hit man with knowledge of Beckett’s mother’s murder – stages a spectacular escape during a court hearing. As police launch a manhunt for Lockwood, Castle and the team uncover evidence of a deeper conspiracy involving a mysterious figure with law enforcement connections who is linked to both Lockwood’s escape and the killing of Johanna Beckett. The search for Lockwood and the quest to identify his co-conspirator leads to a shocking and deadly conclusion.