Adventure Time - Season 5 Episode 38 Red Starved They’re not righteous, they’re wrongteous!
Overview: 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!