Sid Ross, the creator of the long running “Saturday Night Tonight” is murdered and found on top of the elevator in the studio. Castle and Beckett quickly learn there are many suspects. 

Mickey Franks (guest star Jaleel White), the show’s star threatened to kill Sid in front of everyone and has been acting unstable. They find him wandering around in a knight’s costume. When they bring him into interrogation he claims they must talk to his attorney, a puppet. But Mickey gets serious when he finds out Sid was murdered. He was only acting crazy to get out of his contract and start his film career and his alibi checks out.

Danny Valentine (Gregory Harrison) is the show’s guest host and he shamelessly flirts with Beckett which moves Castle from being a fan to being a smug, no talent, playboy. The musical guest is Carly Rae Jepsen who performs on stage. Rick is a fan.

Later, Beckett and Castle realize that someone had kidnapped Sid’s ex-wife and he had withdrawn $4 million for the ransom. Turns out his business manager, Gene Vogel had been embezzling the money for years and needed a way to put it back before he got caught. When it all went wrong, he killed Sid.

Back home, Martha prepares for previews to begin on her Broadway play and gets cold feet. She tells Castle that she hasn’t been on Broadway in 20 years and she’s not ready for this. She’s going to back out. Rick tells her, “Absolutely not!” No one gives you second chances, you earn them and Martha has earned this. Afterwards, Martha comes to the precinct to share the Tweets from her first performance. Public opinion is that she was amazeballs.