While investigating the murder of a cruise ship dancer, Beckett and Castle discover a larger conspiracy. Meanwhile Castle is determined to find out what it is Beckett is hiding from him.
- Amoral Attorney: Caleb Brown appears at first to be just another public defender. In reality he works for LokSat, using his access to jailed drug dealers to pass on orders from his superiors.
- Call-Back: Vikram manages to link the heroin on the ship to Vulcan Simmons' former organization, now being used by LokSat.
- Dueling Hackers: Working with Castle, Hayley tries to hack into Vikram's server after using Castle's call to Beckett as a trojan to get around the initial firewall. Vikram notices and immediately begins defending the server and tracing the source of the intrusion. Hayley tries to stop him by overloading his computer with cat videos, but it doesn't work and they trace the hack to Castle's office. Beckett then calls Castle and they each fish for information from the other. When that fails, Vikram wipes Castle's servers just before the last firewall is breached.
- Easily Forgiven: After Beckett goes to Castle's apartment to apologize and offers to let him in on her investigation, she's forgiven, and is then led to the bedroom for some "very naked punishment."
- Hollywood Hacking: Both Hayley's attempt to hack into Vikram's server and Vikram defending against the attack, complete with visual on-screen representations and lots of rapid typing.
- Mid-season Finale: This episode resolves Castle and Beckett's separation plotline and introduces a new player in the LokSat arc before the season goes on winter hiatus.
- Suicide by Cop: The cartel lieutenant Leo pulls out a gun to provoke Ryan and Esposito into shooting him dead instead of being taken into custody and betraying his employers.
- "The Reason You Suck" Speech: Castle delivers one when he confronts Beckett for lying to him about the LokSat investigation and cutting him out ostensibly to protect him:Castle: You wanna know what hurts the most? You could've come to me with everything, broken us up just like you did. Only it would have been a cover. And together, in secret, we could have taken this guy down. Only that thought never even occurred to you. Because deep down inside, you like being broken and you need this obsession. And no matter what I do, I can't change that. Only you can, Kate.
- She Knows Too Much: Lara was killed because she accidentally stumbled upon a heroin smuggling ring run by the cartels while looking into illegal dumping done by the cruise line.
