Evidence at a crime scene suggests that a murderous Bigfoot is stalking the streets of New York City. While Castle indulges in his knowledge of cryptozoology, Beckett, Ryan and Esposito decide to follow much more mundane (but much more realistic) theories, only to hit a wall that makes them wonder if Castle's bizarre theories might actually be right this time.
- Ax-Crazy: Chase Diggins is a mentally unstable hunter who wants to kill all Bigfoots.
- Believer Fakes Evidence: Castle and Beckett fall into a Bigfoot trap while looking for a murder suspect. Then they encounter Bigfoot. Who also falls into the trap. And then unmasks, revealing himself to be Dr. Daryl Meeks, who was faking being Bigfoot for the purpose of, as he claimed, "drawing in Bigfoot". He claimed to hear yowls and tapping earlier, signature sounds of Bigfoot. Ironically, viewers know those were Castle, who is also a believer in Bigfoot, and was also trying to draw out the mythical creature.
- Booby Trap: Castle rigs one up in his fridge when he discovers food going missing. The culprit turns out to be Alexis, who had spent all of her allowance funding a friend's environmental project and had no money left for food as a result. Castle later falls into one himself while in the forest looking for a suspect.
- Call-Back: After Castle and Beckett fall in the Bigfoot trap, he notes that that's not good for his knee (which was broken in the previous episode.
- Evil Teacher: Justine's professor was stalking her and after killing the girl, took her pendant as a trophy.
- Hook Hand: Chase's reason for his revenge on Big Foots because one attacked and took his hand away.
- Interrupted Intimacy: Alexis triggers Castle's booby trap right before he and Beckett get intimate in the other room.
- Laser-Guided Karma: Beckett jokes that her and Castle falling into a pit trap could be karma for Alexis falling victim to Castle's booby trap.
- No Good Deed Goes Unpunished:
- One of the witnesses lampshades this. He was a felon who dumped the still living victim outside a hospital in an attempt to save her while keeping suspicion from himself.
- Alexis spends all of her allowance on a friend's project, which means she can't afford to buy food and has to sneak it from Castle's fridge at night.
- Only Sane Man: Beckett and Esposito plays this when Castle and Ryan are indulging in Bigfoot existing.
- Revealing Cover-Up: The professor's killing of the Victim of the Week ends up exposing his role in the murder of her roommate a year earlier.
- Roaring Rampage of Revenge: Chase vows vengeance on all sasquatches for severing one of his hands.
