After being challenged to a video game battle by Wendy's boyfriend Robbie, Dipper is shocked when his favorite playable fighter, Rumble McSkirmish, comes to life to defend him. But Dipper soon loses control over Rumble McSkirmish and has to find a way to stop him.

It's Gravity Falls' version of Halloween in Summer with Jack-o-Melons and lots of trick-or-treating. Dipper and Mabel are excited to join in on the fun, but when Wendy casually mentions that trick-or-treating is for kids, Dipper's whole outlook on the evening changes. The night gets even more complicated when a monster that Dipper accidentally insulted makes them fulfill his candy quota by night's end or else he will eat them.