Princess Bubblegum subjects Flame Princess to a series of tests to gauge FP's fiery tendencies. But when there's an emergency at the treehouse, and PB leaves Cinnamon Bun to watch Flame Princess, her experiment might literally backfire in her face.

When Finn starts sleepwalking and dreaming about the Green Lady he filed away in his memory vault, Jake and BMO help him tap into his repressed memories to uncover a secret past. Who is the Green Lady? And how is she connected to Finn?