Bill returns in the form of a human with his brother, Will to atone for his sins. Stan, knowing that Bill must have given up his power willingly to be able to do this, takes Will and Bill into the Mystery Shack then, invites Dipper and Mabel to come for another summer. Taking the offer, Dipper and Mabel return to Gravity Falls. Meanwhile, Bill has to take in a new identity in front of Dipper and Mabel so that he will be accepted among his peers while he is living at the Mystery Shack. Will Dipper and Mabel find out about his big secret? Or does Bill have more to hide than we think?