While investigating the murder of a young woman, Castle and Beckett find evidence that links her death with Senator William H. Bracken (guest star Jack Coleman returns), the man responsible for Beckett's mother's murder. Determined to finally bring Bracken to justice, Beckett soon realizes that things are far more complicated than they seem.
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
While investigating a shocking ritualistic murder, Beckett and her team uncover surprising evidence linking Castle to the killing. As the evidence against him mounts, loyalties are tested, and when surprising revelations come to light, Beckett begins to wonder how well she really knows her new lover and partner of four years.
When a powerful divorce attorney who only represented women is murdered, Castle and Beckett are confronted with a plethora of angry ex-husbands, any one of whom could be the murderer. Meanwhile, Castle's ex-wife (Darby Stanchfield, "Scandal"), Meredith, moves into the loft to take care of Alexis while she recovers from Mono, and to make matters worse, Beckett is also forced to move in while her apartment is being fumigated, causing tension, humor and more than a little awkwardness.
After four seasons of "will they" or "won't they," Richard Castle and Kate Beckett finally gave in to their feelings for each other in the much anticipated Season 4 finale. Season 5 picks up on the proverbial morning after, with Castle and Beckett facing new questions -- Was this a one-time fling, or are they now a couple? But before they find the answers, they must take on the forces responsible for Beckett's mother's murder that now threaten Kate Beckett's life.
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.
Castle & Beckett get an up-close-and-personal view of a "Real Housewives"-esque reality TV series, "The Wives of Wall Street," when they investigate the murder of the show's rising young star. Meanwhile, Castle's attempt to give Beckett a Valentine's Day gift goes horribly wrong.
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.
Castle and Beckett's plans for a romantic weekend in the Hamptons are interrupted when a dying man stumbles into Castle's backyard, collapsing into his pool. Unable to escape the lure of the investigation they join up with the small town's well-intentioned, but inexperienced sheriff to find the killer.
When a young woman is mysteriously murdered, Beckett and Castle discover her death may be linked to a repossessed storage unit up for auction. Was the unit connected to her death? Was something inside it worth killing for? The investigation leads Castle and Beckett to colorful “Storage Wars”-like treasure seekers and Manhattan socialites as they uncover the shocking truth.