When an up and coming DJ is killed at a pop star's album release party, Beckett and Castle must dive into the raucous world of New York's music industry. Then, when the investigation leads to a troubled teenager, Esposito takes the kid under his wing, hoping to put him on the right track before it's too late.
When a bearded, rotund man in a red Santa suit with an ID reading Kris Kringle falls from the sky in Central Park, Castle and Beckett are on the hunt to find the person who killed Santa. But everything isn't holiday cheer, as they discover St. Nick may have been more naughty than nice. Meanwhile, Castle and Beckett prepare for their first Christmas together
When a body is found at a sci-fi convention, Castle and Beckett are warped into the heart of fandom -- a world of egotistic celebrities, diehard costumed fans and enough drama for two galaxies.
When a man is found dead in an industrial cake mixer, Castle and Beckett trace the murder to an Irish gang in Staten Island and a beautiful bar owner named Siobhan O'Doul (guest star Cara Buono, "Mad Men"). Much to everyone's surprise, Detective Ryan has a complicated history with Siobhan and the Staten Island crime family from his days working undercover in narcotics. When the case hits a dead end, Ryan must go back undercover to expose the killer, complicating his relationship with his wife.
When the lead guitarist of a rock band is murdered, the documentary crew that were following the band turn their cameras on Castle, Beckett and the team as they try to solve the case. The result is a documentary style episode of “Castle,” which offers us a unique glimpse at our characters as they navigate a world that goes far beyond the rock & roll stage.
When a young woman appears to have literally been scared to death three days after watching a "haunted" DVD, Castle and Beckett delve into one of their creepiest cases yet. To make matters worse, Castle becomes convinced that he too is marked for death when he accidentally watches the cursed video. Master of horror Wes Craven makes a special quest appearance.
In the first of a two-episode story arc, Castle & Beckett begin a murder investigation that also exposes a plot to kidnap the daughter of a wealthy Middle Eastern businessman. Dylan Walsh ("Nip/Tuck") guest stars as FBI Agent Harris, an even-keeled professional brought in to help find the kidnappers.
When Castle and Beckett find giant footprints at the site of a vicious murder, the team is forced to confront the unlikely theory that Bigfoot is the killer. But as they trek into the world of primate research, big game hunting and mythological creatures, they realize that finding the man (or beast) responsible may put them on the endangered species list.
In the aftermath of a disastrous “Meet the Parents” dinner, a bickering Castle and Beckett are sent to retrieve the only witness to a murder. But when they get ambushed, they’re forced to take the witness on the run. Stranded in the middle of the night in a bad part of town, with no phone, badge or gun, Castle and Beckett must find a way to protect him from a team of mobsters who want him silenced -- that is, if they don’t kill each other first.
When Beckett is assigned to protect Erik Vaughn, a charming billionaire entrepreneur whose life is in danger, she's forced to reflect on her relationship with Castle which has begun to plateau. Meanwhile, consumed with jealousy, Castle goes to extraordinary lengths to solve the case and separate the two of them.