Contains spoilers for this episode and earlier episodes.
Pacifica asks Dipper to remove a ghost from her family's mansion before its exclusive annual party. He dislikes the Northwests but agrees in exchange for invitations for Mabel, Candy and Grenda. Dipper and Pacifica confront the haunting together, and he traps the ghost in a silver mirror. On his way out, the spirit explains its grievance. A lumberjack helped build the mansion after being promised that ordinary townspeople could share its celebrations. The Northwests broke that promise, leaving workers outside as a fatal storm swept through. Before dying, he vowed to return if the gates remained closed. Pacifica's parents hired Dipper to evade the curse rather than honor their obligation.
Angry at being used, Dipper releases the ghost, which returns to the party and turns the guests into wood. Pacifica finds a hidden record of her family's crimes and fears that she is no different from them. Dipper urges her to choose for herself, then is transformed while trying to fight the spirit. Pacifica defies her parents and opens the gates to the town, fulfilling the old promise and ending the curse. The guests recover, and the party becomes a celebration anyone can enter. Grenda also wins the interest of a visiting baron by being herself. McGucket arrives with the repaired laptop and a warning of catastrophe, but Dipper hopes the urgent discussion can wait until tomorrow.