Finn and Jake stumble upon a cave-dwelling society of humans, long thought to be all but extinct, but problems arise when the village leader decides to eat the Candy Kingdom!
- A God Am I: On seing the hyoomans, Jake says he and Finn could rule them like gods. Angry gods.
- Appropriated Appellation: The eponymous character unwittingly names herself when Finn asks her what her name is, and she's still struggling with the word "Sun": "Suh... Sun."
- Big Eater: Susan and her people once they overcome their fear of the surface.
- Bittersweet Ending: Finn and Jake saved the Candy Kingdom but Finn may still be the Last of His Kind.
- Cowardly Lion: Susan Strong's reaction to everything on the surface world is near-panic, but once she and her tribesmen acclimate to the surface world, they quickly become dangerous.
- Exact Words: Finn tells Susan she can't eat the Candy People, but Susan takes it to mean she just can't eat Peppermint Butler.
- Last of His Kind: Finn tries not thinking about it, because otherwise he gets "all soul-searchy".
- Level Ate: As it turns out, everything in the candy kingdom is candy. Finn offers Susan some Sidewalk Brittle, instead of Peppermint Butler.
- Open Mouth, Insert Foot: Princess Bubblegum keeps accidentally bringing up Finn's status as the last human.
- Platonic Cave: The people are afraid of the Shadows until Susan teach them they are harmless.
- Shout-Out: The design of the hatch is similar to that in Lost; the title card in the page image is a direct reference to that series' infamous Season 1 cliffhanger.
- Tomato Surprise: The "humans" are actually humanoid fish-people who call themselves "hyoo-mans". Except maybe Susan...
- The Un-Reveal:
- PB mentions her uncle Gumbald tried cutting down lots of trees, but doesn't explain why.
- The hyoomans are revealed to be fish-people when their hats are burnt off, except for Susan's, which remains unburned, and she runs away without giving Finn any answers as to who (or what) she is.
- Ye Olde Nuclear Silo: Implied to be where Susan's people have been living.