Mabel and Dipper, now adults move to Gravity Falls in the Mystery Shack with Soos and Melody. Unfortunately, no one knows what happened to Stanford and Stanely, no one has heard from them since they left to the Antartic Ocean. Many people say they were killed by the monsters in the sea, but Dipper is determined to somehow go out in the ocean and find them. Mabel on the other hand, believes they're A Okay still being her positive self, but when an article shows up in the news about their Grunkles and the fact they're probably dead, Mabel gets worried and scared. She's so terrifyed she brings Bill Cipher back to life using one of Dippers published books, "Gravity Falls down-right terrifying secrerts," to find out about what happened to her grunkles. Bill and Mabel make a deal that If she serves as his slave for 364 days, he will save her whole family, for Bill also has plans of killing off Dipper since he's getting close to finding out what happened to they're grunkles, while searching desperately for his missing sister. As Mabel serves for the cruel demon, and as he tortures her in horrible ways for entertainment, he soon starts to feel, 'weird'. He soon relizes he has fallen in love with one of his enemys. And that enemy hates him with all her heart. What happened to Stanley and Ford? What will happen to Dipper? Apperntly Soos and Melody aren't important at all! Or are they? What romance will blossom between Bill and Mabel, because something has to happen if this book is titled, 'Mabill'.