A young man from a once-rich family fallen on hard times is found floating in a rowboat in a Central Park lake, shot in the chest. The investigation takes Castle and Beckett into the private academy the boy attended, where they find themselves trying to break into his intensely close-knit group of friends — who, it transpires, are themselves quite adept at scheming, manipulation and evasion. In order to find the killer, Castle and Beckett will have to pick their complex web of lies apart.
The Castle episode "Hedgefund Home Boys" provides examples of:
- Bitch in Sheep's Clothing: Don't let the killer's "cooperative suspect" act fool you, because just under the surface, he's a manipulative jerk who killed off a couple of his 'friends' for kicks. When his true colors show, it's hard to believe he was remotely nice in the beginning.
- Chekhov's Gun: The Bluetooth software the friends use to link their phones puts the killer at the scene of the crime.
- The Dog Was the Mastermind: The killer turned out to be the one kid who seemed to be cooperating with Beckett and Castle and telling the others they should tell the truth about what happened. He turned out to be a real Jerkass.
- Driven to Suicide: The kid who held the gun that killed Donnie goes to the park and commits suicide. Rapidly revealed to be a false lead, as he was so drunk he probably wasn't even conscious when someone put the gun to his head and made it look like suicide.
- Hate Sink: By the end of the episode, you'll be aching for the killer to get his comeuppance.Castle: I hate that kid!
- Heel Realization: Castle answers his phone with "Who was murdered and was it gruesome?", but loses his smile when he learns he was joking about the murder of a teenage boy.
- Incorruptible Pure Pureness/Felony Misdemeanor: Castle gets paranoid about his teenage daughter having done something illegal, like drugs. Alexis assures him that she's not and hasn't been in any kind of trouble. The next morning, Alexis wakes him up, tearful and guilt-ridden about having lied to him in their earlier heart-to-heart, and painfully forces herself to confess the truth... she once jumped a subway turnstile without paying when she had a desperate need to catch the train. (The next day she swiped her card twice and didn't ride, just to make up for it.) He punishes her. With mandatory ice cream for breakfast. She has to punish herself with being grounded for a week. After the trip to DC with her friends.Castle: Tough but fair.
- Motive Rant: Played with; Castle was able to read the suspect's motives so well that he did the rant for the perp - thus getting a confession from him, when the suspect gets caught up enough to confirm the rant with "exactly".
- Never Suicide: One of the victim's friends, and his apparent (accidental) murderer apparently commits suicide. He was really murdered by another teen, a Dexter wannabe who also planned the first friend's murder.
- Noodle Incident: According to Castle, last time Martha was left alone, she threw a wild Cinco de Mayo party that left lime shards in the wall.
- Not What It Looks Like:"It's exactly what I think."
- Papa Wolf: Castle has a little more trouble keeping his cool with his case than he did with the earlier cases, because the victim is a teenager, like his daughter.
- Riches to Rags: The victim's parents used to have a lot of money, but fell on hard times thanks to some bad investments. His prep school was willing to put him on scholarship thanks to gratitude for their past donations.
- Shout-Out: Before pulling the trigger and accidentally killing Donnie, Max says "Goodbye, Mr. Anderson."
- Smug Snake: The murderer. Taunts Beckett and Castle about their lack of evidence. However, then he gets so caught up in Castle recounting how powerful and intelligent he was throughout his plan that he confirms himself as the murderer.
- Take That!: Castle, worried about kids doing drugs and putting themselves in danger, asks Alexis about her friends and what they're doing, including "partying Winehouse style".
