Castle is captured and forced to work with strangers to solve deranged puzzles and mind games, while Beckett and the 12th Precinct must race against time to rescue Castle and catch a killer.
When the son of a Russian diplomat turns up murdered, Beckett and Castle find themselves in a dangerous game of international crime and punishment, with Castle having to entertain a jovial Russian security officer who winds up more involved than anyone planned.
Castle finally gets his day in court when he takes the stand as the key witness to a murder from five months ago. But when new information suddenly arises, he and Beckett must race against the clock to prevent a miscarriage of justice.
When a body is found in the theater of Martha’s latest show, Castle and Beckett’s investigation leads them into the unexpectedly dangerous world of competitive a capella.
Castle and Beckett investigate the murder of a cruise ship entertainer, only to find themselves trapped at sea with the killer.
In order to hunt down the brutal murderer of a grifting seducer, Castle & Beckett must investigate New York’s elite. Meanwhile, Castle plans to surprise Beckett on their one-year wedding anniversary.
Detective Slaughter (guest star Adam Baldwin) returns to enlist Castle’s help in solving a high-stakes robbery case. But when a body is found linked to the crime, Slaughter becomes the number one suspect in the heist turned murder, while Castle has to determine whether he’s guilty or help to prove he’s innocent.
When a priceless work of art is stolen and its transporter murdered, Castle and Beckett must work with the key witness to track down the painting and sniff out the killer.
When Castle’s idol, a famously reclusive author, turns up dead, Castle is determined to solve his hero’s murder. But as he and Beckett dig deeper, they discover that truth is stranger than fiction.
When the body of a local college fraternity student is found gruesomely murdered, Castle has to go undercover as a professor in order to gain access to the victim's world. However, he and Beckett soon discover that behind the fun and games of college are some darker secrets the university wants to keep hidden.