Season synopsis
Contains spoilers for this season and earlier seasons.
Finn and Jake’s early quests in Ooo turn ordinary rescues into peculiar problems. They help Princess Bubblegum contain candy zombies after her experiment goes wrong, travel to Lumpy Space to find a cure after Jake is bitten by Lumpy Space Princess, and free princesses the Ice King has imprisoned. On a search for the Crystal Gem Apple, they bring Tree Trunks along; she bites the apple and disappears, leaving the friends without her. Finn later earns the Enchiridion by completing tests that prove his heroism, and the book becomes a tool in later adventures.
The brothers meet Marceline when she claims their treehouse, and Finn learns to look past her vampire reputation. Other scrapes include exposing Ricardio as the Ice King’s detached heart and sending thawed businessmen back into an iceberg after their efficiency makes them dangerous. In the finale, the Soft People, Cube People and Spiky People each report that a creature resembling Jake has eaten their gold. Finn searches for the Gut Grinder while Jake becomes convinced he may be the culprit. Their trap draws out the monster; Jake fights it, then the Spiky People discover the creature is Sharon, the Spiky Chief’s wife, wearing a costume to steal gold for shopping. They return the stolen gold.