Mabel returned to Gravity Falls when she turned 16. After great uncle, Stanley Pines, passed of cancer, Dipper went off saving the world with Stanford, in other mysterious places. Grenda moved to her newly wedded husband home. Candy went to Tokyo to continue her dream job. Mabel was all alone. Soos was too busy with the Mystery Shack and Wendy moved to Florida. Mabel was truly alone. Until, she found herself caught up in an unlikely situation she hoped would never come to be.