All aboard! Finn and Jake discover a train where every car is a dungeon filled with a new foe for Finn to fight. Jake quickly gets bored and wants to leave, but Finn is having the BEST time and doesn't want to leave... ever!

Finn, Jake and Marceline are trapped in an underground cavern with no red in sight. If Marceline doesn't feed, like ASAP, she will turn into a vampiric beast and suck out all of Jake's blood! So, Finn heads off to explore the cave and find something red to satiate her until they can be rescued. But time is running out!