The investigation into the death of a famous dog trainer leads to a reality-TV star.
When a woman is found dead in her car, the investigation leads to New York Mayor Robert Weldon (Derek Webster), one of Castle's longtime friends.
When Castle and Beckett investigate the death of a ladies' man, a twist in the case may disrupt Ryan's wedding.
Beckett and Castle wake up handcuffed together in bed in a locked room with no memory of how they got there.
The team searches for a sniper who is terrorizing New York; Beckett tries to hide her worsening PTSD from Castle and the detectives.
When a casino owner is murdered at an abandoned warehouse, suspects emerge in New York and Atlantic City; during the investigation, Castle throws an impromptu bachelor party for Ryan.
Martha and Castle are held hostage by bank robbers dressed in hospital scrubs; Beckett's rescue efforts are hindered by a strict hostage negotiator (Dean Norris).
Castle and Beckett investigate the murder of a ghost hunter who was looking into a haunting at a New York mansion.
A sexy insurance investigator -Kristin Lehman- with a secret helps Castle and Beckett when a valuable sculpture is stolen and someone is murdered.
When a young woman is shot to death, Beckett and Castle learn the gun used was the one a serial killer stole from Detective Ryan.
Castle and Beckett investigate a crime scene that involves a large pool of blood but no victim; Alexis receives news about Stanford.
Castle and Beckett suspect a costume-clad vigilante is responsible for the mysterious murder of an ex-con.
Detective Beckett struggles to survive; Castle tries to identify the shooter; Ryan and Esposito try to adjust to the new captain.
An all new season kicks off with exciting discoveries and challenging cases and a tough, new NYPD captain shaking things up.
A professional hit man (Max Martini) with information about the murder of Beckett's mother escapes during a court hearing; Castle and the team uncover a deep conspiracy.
After a contestant in a beauty pageant is found strangled, many suspects turn up, including jealous fellow contestants, the pageant's sponsor (Michael McKean), and the show's host (Sasha Roiz).