Stan throws a big weekend party to promote the Mystery Shack. Dipper makes clones of himself to impress Wendy. Mabel fights for the Party Queen title in honor of her two friends.

The kids, along with Old Man McGucket's help, discover there is a secret society in Gravity Falls.

Dipper, Soos and Wendy must save Mabel from a strange new world, while Bill's forces plan their next move.