"Once Upon a Crime" - 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.
"Murder, He Wrote" - 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.
"The Way of the Ninja" Castle and Beckett investigate the mysterious murder of a Japanese ballet dancer, they end up being targeted by a ninja assassin.
When an art dealer is gunned down in his gallery, Castle & Beckett discover that a bullet is inexplicably missing from the crime scene.
When Castle’s idol, a famously reclusive author, turns up dead, Castle is determined to solve his hero’s murder. But as he and Beckett dig deeper, they discover that truth is stranger than fiction.
Castle and Beckett investigate the hit-and-run death of a bike messenger, brutally murdered to prevent him from delivering a package, the contents of which could free a wrongly convicted man from prison.
When Castle and Beckett learn that a murder victim may have been poisoned at an Old West-style resort, they visit the resort posing as newlyweds to uncover the truth.
Castle returns to the City of Angels in search of answers about his missing time. But things take a deadly turn when he’s recruited by the legendary Greatest Detective Society to help solve a murder.
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.
"Undead Again" - 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.