Get a Clue: Castle and Beckett investigate the ritualistic murder of a woman reminiscent of 'The Da Vinci Code'. Meanwhile, Castle struggles to accept Alexis's decision to move in with Pi. (S6 Ep6)
Like Father, Like Daughter: Alexis is working with a criminal review organisation to prove a death row inmate's innocence. But with his execution date nearing she enlists the help of Castle. (S6 Ep7)
A Murder is Forever: The investigation into the murder of a relationship therapist reveals the lives and relationships of her elite clients, leading them to the discovery of a valuable jewel. (S6 Ep8)
Disciple: When murder victims, who bear a striking resemblance to both Lanie and Esposito, are found during an investigation the team worries that a killer is targeting the 12th precinct. (S6 Ep9)
Secret's Safe With Me: When a young woman is found murdered, Castle and Beckett uncover a crucial link to a repossessed storage unit and soon reveal big city 'storage wars'. (S5 Ep3)
The Way of the Ninja: When a Japanese ballerina is mysteriously murdered, Castle and Beckett's investigation into her secret life leads them straight to the top of the Yakuza. (S6 Ep18)
The Greater Good: The investigation into the death of a Wall Street trader takes a shocking turn when the victim is revealed to be an undercover informant for the U.S. Attorney's office. (S6 Ep19)