(Part 2) The 12th Precinct and Castle try to stop Nieman and Tyson from claiming Beckett as their next victim. While Tyson captures Castle too, Castle reveals that it was a ploy to draw Tyson into the open where Esposito kills him with a sniper rifle. Using his phone, they track Nieman only to find Beckett escaped and killed her. At the end, Castle's ban is lifted and he is reinstated as Beckett's consultant/partner at the precinct.
Tropes that appear in this episode:
- Asshole Victim: Both Serial Killer 3XK and his accomplice Dr. Nieman are killed in this episode, and oh, is it a fate well deserved.
- Badass in Distress: Beckett wakes up strapped to an operating table with a Mad Doctor standing over her.
- Bait-and-Switch Comment: "That was the stupidest, most reckless thing you've ever done. Thank you."
- Batman Gambit: Castle decides to allow 3XK to win in order to lure him out, playing to Tyson's need to constantly prove himself smarter than him.
- Earn Your Happy Ending: Castle gets reinstated as Beckett's consultant and 3XK is finally killed.
- Evil Is Petty: For once, this works in the heroes' favour; lost for leads, Castle goes to Tyson's former cellmate and accomplice Marcus Gates for leads, only able to offer Gates the 'promise' that Tyson will suffer as he and Gates both know that Castle can't arrange for him to receive any additional luxuries given his list of crimes.
- Godzilla Threshold: In response to Tyson's return and kidnapping of Beckett, Castle sends his family to Europe.
- Laser-Guided Karma: After Castle makes one final taunt, 3XK gets shot by the unknown assailant which turns out to be Esposito.
- Once More, with Clarity: The preparation scenes leading up to Castle's arrival at 3XK's house are revisited as Castle taunts Tyson, showing that Ryan and Esposito had given him a hidden earpiece and were tracking him the whole time.
- These Hands Have Killed: Beckett has killed bad guys before but stabbing Nieman to death with her own scalpel is clearly far more disturbing.
- Unishment: As part of the deal to get his assault charges dropped, Castle is required to serve 1,000 hours of community service...as Beckett's consultant at the NYPD.
- What Happened to the Mouse?: The last we see of Amy Barrett is Castle tying her up at gunpoint and locking her inside the trunk of his car.
