An all new season kicks off with exciting discoveries and challenging cases and a tough, new NYPD captain shaking things up.
Detective Beckett struggles to survive; Castle tries to identify the shooter; Ryan and Esposito try to adjust to the new captain.
Castle and Beckett suspect a costume-clad vigilante is responsible for the mysterious murder of an ex-con.
Castle and Beckett investigate a crime scene that involves a large pool of blood but no victim; Alexis receives news about Stanford.
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.
A sexy insurance investigator (Kristin Lehman) with a secret helps Castle and Beckett when a valuable sculpture is stolen and someone is murdered; a rich museum benefactor (Jessica Tuck) garners suspicion.
Castle and Beckett investigate the murder of a ghost hunter who was looking into a haunting at a New York mansion.
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).
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.
The team searches for a sniper who is terrorizing New York; Beckett tries to hide her worsening PTSD from Castle and the detectives.
Beckett and Castle wake up handcuffed together in bed in a locked room with no memory of how they got there.
When Castle and Beckett investigate the death of a ladies' man, a twist in the case may disrupt Ryan's wedding.
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.
The investigation into the death of a famous dog trainer leads to a reality-TV star.
Castle and Beckett must investigate a mysterious case from 1947 in order to solve the present-day murder of a treasure hunter.
Castle and Beckett discover the killer they are pursuing is part of an international conspiracy and they must work with a CIA agent with whom Castle has a history
Beckett and Castle must stop a series of events that could result in a war.
When two women are found dead dressed as fairytale characters, Castle and Beckett must race to find the killer before he strikes again.
When Odette Morton, a contestant on the hit competition show “A Night of Dance,” is found murdered in her dressing room, Castle and Beckett must navigate the case’s many twists and twirls without stepping on each other’s toes.
When a bomb kills five people at a protest rally, Beckett and Castle try to solve the case by reconstructing the 47 seconds prior to the explosion.
A devilishly handsome detective from Scotland Yard, Simon Hunt (Brett Tucker, "Off the Map," "Spartacus," guest stars), teams up with Castle & Beckett to find the person responsible for the murder of his friend's daughter. Also, Charles Shaughnessy ("Days of Our Lives") plays Nigel Winthrop, the Deputy General at the British Consulate whom Castle & Beckett suspect is up to more than just ambassadorial balls and diplomatic luncheons. Meanwhile, Lanie convinces Beckett that she needs to make a move on Castle before it is too late.
With tensions rising between Castle and Beckett, Castle finds himself a new partner -- Detective Ethan Slaughter (guest star Adam Baldwin, "Firefly"), a tough and colorful cop from the city's gang unit. But Castle gets more than he bargained for when Slaughter shows him a grittier side of police work that puts Castle in the line of fire like never before.
When Castle and Beckett investigate the murder of a man with human bite marks on his body, Castle's wild theories start flying. But none are as wild as what their only witness insists happened - a Zombie attack. As the evidence pointing towards an undead assailant piles up, the team plunges into New York's Zombie subculture to find the killer and bring him in dead, undead or alive.
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.