When the murder of an Army veteran puts Beckett on the trail of the man who shot her, Castle must decide how much he's willing to sacrifice to keep her safe. As secrets are revealed and feelings are put on the table, the lives of the detectives at the 12th Precinct may never be the same.
When a woman dressed as Red Riding Hood is found dead in the woods with claw marks covering her body, and soon after a murdered Snow White is discovered with a poison apple in her hand, Castle & Beckett find themselves on a Grimm hunt to catch a fairytale killer before he kills again. But nothing is as it seems in a case filled with deceit, betrayal, secrets and murder.
In a riveting opening that picks up just moments after last season's climactic finale, Detective Beckett (Stana Katic) fights for her life as Castle (Nathan Fillion), plagued by guilt over his role in the events, struggles to uncover who's behind her brutal shooting. Meanwhile, back at the precinct, Ryan (Seamus Dever) and Esposito (John Huertas) have to adjust, as Victoria "Iron" Gates (Penny Johnson Jerald, "24") becomes the precinct's new uncompromising Captain.
Derek Webster (“Desperate Housewives,” “Damages”) guest stars as Mayor Robert Weldon, Castle’s longtime friend and the Mayor of New York City. It was Mayor Weldon’s political clout that allowed Castle to partner up with Beckett. But now, when a woman is found dead in a car that traces back to the Mayor’s motor pool, that partnership comes under fire as the scandal surrounding the investigation threatens to bring down Weldon’s administration
During the investigation of the murder of an Atlantic City casino owner at an abandoned warehouse, strong leads emerge for the team in both New York and Atlantic City. As Beckett and Capt. Gates work the New York leads together, Castle naturally chooses to join the detectives for the road trip to "America's Playground," hoping to help solve the case while throwing an impromptu bachelor party for Ryan.
When Castle and Beckett investigate the killing of a treasure hunter, they discover the case is linked to a mysterious homicide from 1947 involving a hard-boiled private detective. Castle realizes the only way to solve the present-day murder is to solve the murder from the past. The 1947 case comes to life through stylized flashbacks, featuring Castle as the private eye and Beckett as a femme fatale
Castle & Beckett confront the possibility of paranormal foul play when a world renown ghost hunter is mysteriously murdered while investigating a haunting at a legendary New York mansion.
When Castle and Martha are taken hostage by a crew of bank robbers dressed in hospital scrubs and using classic television doctor names (Trapper John M.D., Dr. Huxtable, Dr. Quinn Medicine Woman and Dr. Doogie Howser), Beckett finds herself on the outside, desperately trying to rescue them -- which proves to be even more difficult with a by-the-book hostage negotiator (guest star Dean Norris, "Breaking Bad") watching her every move. Castle becomes the de facto leader of the hostages, which includes Barry Livingston ("My Three Sons"), and discovers that the robbery is actually a skillfully orchestrated distraction for an even more sinister plan. But with Castle stuck on the inside and Beckett on the outside, will either be able to foil the bank robbers' plans before it is too late?
When an ex-con is mysteriously slain in an alley, Castle and Beckett believe a vigilante is behind the murder. But efforts to identify their suspect are thwarted when they discover that he roams the city in a Superhero costume — and may indeed be a Superhero. Can they capture and unmask the killer before he strikes again?
When a famous dog trainer is killed, the investigation keeps coming back to charismatic reality TV star Kay Cappuccio (guest star Hilarie Burton, "White Collar"). Kay, a favorite of tabloids and gossip websites the world over, has achieved stardom without possessing any discernible skill or talent. But there seems to be more to her story than she is letting on.