Kate Beckett is faced with the toughest case of her career after finding Castle's car engulfed in flames.

While the team investigates the murder of a toy company CEO, Castle uncovers a lead to his mysterious disappearance, launching him into a dangerous investigation of his own.

When a pool shark is murdered by an unseen force, Castle and Beckett uncover evidence that the killer may have paranormal powers. Meanwhile, Castle and Beckett attempt to get their lives back to normal following his disappearance.

Beckett and Castle investigate the shooting of an ice cream vendor and clues lead them to suspect that an unknown second grade child might be able to help them solve the case; Castle goes undercover at a school to try and find the student.

When a web celebrity is murdered, Castle and Beckett explore the flashy world of internet fame, but when the killer posts pictures from the crime scene on a photo-sharing site, they realise they are up against a social media sociopath who may strike again.

Castle and Beckett are motivated to be wed after a murder investigation dispatches Castle into an alternate universe where he's never met Kate, Ryan or Javier.

Castle and Beckett pose as newlyweds at an Old West-style resort to discover the truth about a murder victim.

When Castle and Beckett stumble upon a wanted terrorist as a prime suspect, the NYPD goes on a manhunt, and the consequences could be deadly for one member of the team.

After Castle finds out that his most beloved 1980's movie star has been murdered, he and Beckett receive aid from a group of older action heroes, and investigate the man's heavily guarded past in hopes that it will lead them to his killer.

Castle works for a mafia don to solve the murder of a mob doctor. Esposito has dinner with Lanie and her parents.

When Castle is prohibited from working with Beckett or the 12th Precinct he gets his P.I. license and shows up at Beckett's crime scene as a private investigator, where things don't go as planned.

While Beckett and her team investigate the murder of a young telenovela actress, Castle is hired by the show's star to follow the case from a different angle.

Hired to look into possible infidelity, Castle unexpectedly witnesses the murder of his client by her husband, but there's no proof the killing took place. Castle and Beckett look for the answers to expose the truth.

Castle and Beckett encounter an old rival, Dr. Kelly Nieman, while looking at clues in a woman's mysterious murder, and then further investigation links an infamous serial killer to the crime.

Stakes rise as the 12th Precinct matches wits with serial killers Jerry Tyson (3XK) and Dr. Kelly Nieman. Castle and the team must crack the case before the killers claim their next victim.

When an astronaut in a Mars simulation is killed, Castle and Beckett don spacesuits and enter the simulation to investigate. Much to their surprise, it seems no one inside and no one outside could have committed the murder.

A Hong Kong Detective works with Beckett and Castle on the murder of an ex-con turned tow truck driver.

Detective Ryan ends up in the middle of an assassination plot when he is on the security detail of a charismatic congressman; Castle and Beckett help Ryan investigate.

Beckett and Castle are faced with a large list of possible suspects when a personal injury attorney known as Richie "The Pitbull" Falco is murdered; a shocking secret deepens the mystery surrounding Richie's death.

A mysterious recurring dream drives Castle and Beckett to seek answers about the two-month period when he went missing. But their search for the truth has deadly consequences.

Beckett must help Castle and Alexis from the ground when the Air Marshal on their flight is found murdered in mid-air.

The creator of a sketch-comedy show is murdered, and the investigation yields a surprising secret.

A death occurs in the woods and Castle becomes obsessed with the case because it reminds him of a pivotal event in his childhood. Beckett reaches a turning point in her life.