Contains spoilers for this episode and earlier episodes.
Bill gains a physical body through the broken rift and transforms Gravity Falls into a landscape of monsters and impossible changes. His allies terrorize the residents while he builds a fortress from the wreckage of the town. Ford tries to stop him with a weapon, but the attack fails. Bill captures him, turns him into a golden trophy and destroys the journals, leaving Dipper without the mentor or books he hoped could solve the crisis. After days of hiding alone, Dipper finds Wendy. Her survival skills provide a refuge, and she persuades him that they still have something worth doing: finding Mabel and bringing her back.
Mabel is trapped in a floating prison bubble guarded by Gideon, who has accepted power from Bill and hopes confinement will make her love him. Dipper and Wendy steal a vehicle and race Gideon's gang through the transformed town, passing through patches of unstable reality. Soos joins them, but the group is surrounded before it can reach the bubble. Dipper stops treating Gideon only as an enemy and asks him to consider what Mabel would actually want. He explains that affection cannot be forced and that Gideon can still choose to help. Gideon turns against Bill, giving the rescuers their chance while his gang confronts the demon's forces. Dipper, Wendy and Soos approach the bubble together, ready to face whatever is inside.