Castle is a guest on the Bobby Mann Live TV show and gets caught flirting with actress Ellie Monroe. When the show ends, Bobby Mann (guest star Tom Bergeron) leans into Castle to say they want him dead. The next day, Bobby Mann is, indeed, found dead. Getting into show business is hard, but getting out can be murder.
Ellie Monroe gives Castle a call so that they can figure out some way to deal with the tragic news of Bobby Mann's death. Ellie's method of mourning involves ripping off Castle's shirt and throwing him down on her bed. What a great coping mechanism! A possibly jealous Beckett thinks Ellie may be using Castle to get the lead in the new Nikki Heat movie. Of course, that would be highly slimy on Ellie's part. And Hollywood folks always have an ethically-sound moral compass, right?
Okay, back to the case. Bobby Mann was taking an anti-depression drug that, when consumed with anything fermented, would be fatal. He had a documented heart condition. The team determines that a killer hid the balsamic vinegar in some cranberry juice that was served to the TV host. Mann's executive producer, Janine Marks, and show sidekick, Hank McPhee, say that Mann was agitated and paranoid the day he died.
Mann made a late night visit to the home to Mickey Reed, the host of Late Talk, the show that follows his show. Apparently the network tapped Reed to take over Mann's timeslot. Reed tells our team that Mann stopped by his apartment to confront him and accused him of being disloyal. As to what, he has no idea.
Castle looks through items found in Mann's pocket. He finds the host's idea notebook with adjustments to his signature phrase as well as a clue that suggests Mann visited a club called The Comic Factory. He was there to check out a hot young comic named Angel Santana. The poisoning must have taken place after he left the club, as Mann didn't order any cocktails. Don't those comedy clubs always have a two drink minimum?
Ryan and Esposito find a compromising photo of Mann with a young intern. A blackmail threat is written on the back of the picture. A closer look at his financials shows that Mann paid $100,000 for a kitchen remodeling; only he never remodeled his kitchen. The money went to a Zach Robinson, a former private eye known for his illegal methods, including blackmail.
Robinson tells Beckett and Castle that Mann hired by him to bug network president Howard Weisberg's office. There's a recording of Weisberg musing about Mann's bad heart and how Mickey Reed would step in nicely if only the ratings-challenged host would drop dead. Weisberg says he threatens to kill people every day. He's a network executive. That's his job! He also has an alibi for the night Mann was killed. He was sleeping with an actress. Her name: Ellie Monroe.
As Castle waits for an "I told you so" moment from Beckett, Ellie leaves the precinct confirming Weisberg's alibi. By the way, Beckett never did rub salt in Castle's open wound. She's not in the gloating mood, as Weisberg's alibi puts them back at square one on the case.
Castle exits the precinct using Mann's signature phrase: "The boys will be back on duty tomorrow night." Castle realizes that, according to Mann's idea notepad, he was altering the line to exclude the word "boys." The only reason to do that is if he was making a change. He was. Mann was going to fire his sidekick and friend, Hank.
Mann knew the network would cancel his show unless he could appeal to a younger audience. That's why he was scoping out Angel Santana at the comedy club. Hank breaks down and admits to killing Mann. They'd been best friends and colleagues for over twenty years; to be tossed aside to reach a younger demographic was too much to take. Told ya show biz can be murder.
With the case closed, Castle says he's heading home for a date. Beckett can't believe it. She goes off on a major rant chastising Castle for continuing a relationship with a woman who so obviously used him. Castle lets out a wry smile before confessing that the date of which he speaks is with Alexis. Gotcha! Beckett can't help but let out a little smile of her own. And even though Castle may be sting just a bit after his experience with a scheming starlet, a hug from his daughter makes everything all right. After all, her love for him could never be an act.