Finn, Jake, BMO, Marceline, and Princess Bubblegum must come together and play music as a genuine band in order to open the gate of the Door Lord and retrieve their stolen items.

Finn, Jake, and some friends attend a dinner with a mysterious host. However, the host then reveals himself as a murderous ghost that will possess the body of one guest to kill everyone else. The night turns from a masquerade party into a terrifying whodunit as the guests start to get murdered one by one.