Marceline and Princess Bubblegum journey to the imposing, beautiful Glass Kingdom, and deep into their tumultuous past, to prevent an earthshaking catastrophe.

Finn and Jake reunite in a remote future and embark on a death-defying adventure.

Follows Peppermint Butler, starting over at the beginning, as just another inexperienced Wizard School student. When mysterious events at the campus cast suspicion on Pep, and his checkered past, can he master the mystic arts in time?