During the investigation of the murder of an Atlantic City casino owner at an abandoned warehouse, strong leads emerge for the team in both New York and Atlantic City. As Beckett and Captain Gates work the New York leads together, Castle naturally chooses to join the detectives for the road trip to "America's Playground", hoping to help solve the case while throwing an impromptu bachelor party for Ryan.
- Asshole Victim: With all of Siegel's cruelty and abuse towards his employees and even his wife, no one sheds any tears over his murder.
- Awesomeness by Analysis: Castle figures out that Charlie is terrified of the mob, whose $10 million he lost.
- Bad Boss: Casino owner Siegel threatens one of his employees that he'll evict her parents if she doesn't sleep with him.
- Blatant Lies: Castle walks in after a night in Atlantic City, after a night of a Wild Teen Party thrown by Alexis.Castle: Hey.
Alexis: Hey. What happened?
Castle: Nothing. What happened here?
Alexis: Nothing. - The Dog Bites Back: Siegel's wife decided to end the years of abuse her husband inflicted on her by hunting him down and killing him.
- Elvis Impersonator: Castle, Ryan, and Esposito did this.
- Even Evil Has Standards: Tommy Moretti is a ruthless gangster but he's also a man of his word and keeps to his end of the agreement when he gets his money back. He's also willing to share what he knows about the night of Siegel's death with the police.
- How We Got Here: The episode opens with Castle getting dragged through an anonymous hallway dressed as Elvis. We then spend half an hour learning how the hell he wound up there dressed like that.
- Karma Houdini: Murderous kidnapper mobster Tommy Moretti gets everything he wants and walks away.
- Jurisdiction Friction: Charlie Turner kicks Ryan, Esposito, and Castle out of his casino when he gets angry. Given they're NYPD in New Jersey, he's well aware of his ability to throw some muscle at them.
- The Mafia: Tommy Moretti, a gambler at the casino and the man whose money Siegel lost.
- Nepotism: Unspoken, but Esposito and Castle clearly feel this way after finding out Ryan made Jenny's kid brother the Best Man for his wedding.
- Noodle Incident: Apparently the last time Castle stayed in the Sapphire, he accidentally set one of the mattresses on fire and covered the drapes in jam.
- Tempting Fate: Alexis's friend Jules tells her that one of the guests is posting about the party on social media, but says that he's unpopular enough that he probably doesn't have many followers. Shortly afterwards, a lot more people show up.
- Wild Teen Party: Alexis tries to stage a girls night. It goes wildly off the rails as soon as she also invites a few boys (specifically to get hot-as-hell jock Brian over).
- Villain of Another Story: Tommy Moretti is a mob boss, somewhat involved in the episode's plot, but he didn't kill Siegel, and is fairly reasonable once he gets his money back.
- You Said You Would Let Them Go: Daniel pleads this to Tommy, who is holding his girlfriend hostage, once he's fulfilled their deal. After a tense pause, Tommy does let her go.
