An astronaut is killed inside a Mars simulation; a discovery results in a shocking turn in the case.
The 12th precinct tries to stop Dr. Kelly Nieman and Jerry Tyson before they claim another victim.
Evidence in a young woman's murder implicates Dr. Kelly Neiman -- Castle and Beckett's nemesis.
A woman hires Castle to see if her husband is cheating on her -- but things take a shocking turn.
Beckett and the team investigate the death of a young telenovela actress.
Unable to work alongside Kate or the 12th Precinct, Castle gets his private investigator license.
Castle and Beckett discover an ER doctor who was gunned down in the street was a mob doctor.
A team of aging action heroes helps Castle and Beckett investigate an actor's murder.
Esposito is among subway passengers taken hostage by a mysterious gunman.
Castle and Beckett go under cover as newlyweds at an Old West-style resort to investigate a murder.
An investigation forces Castle into what seems like an alternate world where he and Kate never met.
When crime scene pictures show up on a website, the investigators worry the killer may strike again.
Castle goes under cover to try to find a child who may have information about a shooting.
The investigation into a pool shark's death reveals that the killer may have had paranormal powers.
As the team investigates the murder of a toy company CEO, Castle engages in his own investigation.
Beckett is faced with the toughest case of her career after finding Castle's car engulfed in flames.