Mabel makes plans for her and Dipper’s 13th birthday party; Dipper ventures below the town and discovers its most shocking secret.

Blendin returns to face off with Dipper and Mabel in a futuristic battle that could trap them forever in time jail.

Dipper wants to correct a mistake he made in the past with assistance from a time machine. Mabel is overjoyed when she wins a pet pig at a fair.