Finn, Jake, and Marceline, on the hunt for Ewlbo—the wizard who gave BMO a computer virus—race to find out the truth before BMO's gone for good. Can Marceline's totally radical hacking skills save the day? Or is something about to go very wrong?! Also featuring the backup stories "The Devilish Devourer of Delicious Delicacies" and "Princess of Rad Hats (Part One)"!