Dipper and Mabel are 16 and are returning to gravity falls for another summer, they expect the usual weirdness of gravity falls and nothing else. and then a demon unexpectedly returns from the dead for a visit...
Dipper returns to Gravity Falls four years later after his first summer there. He has big plans for the summer and is excited for what is to come, but his hopes die out after getting into a fight with Mabel. Fortunately for Dipper, his plan for the summer may be saved... for a price. (Eventual BillDip)