When Dipper and Mabel hear rumors of a sea monster that lives at the bottom of the local lake, they enlist Soos to take them on a boating expedition to prove it really does exist.

Dipper is invited by Wendy and her teen friends on a trek that leads to an abandoned convenience store that may be haunted.

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.

Dipper and Mabel go trick-or-treating in the summer and encounter a candy-loving monster who threatens to devour them if they don't bring him sweet things to eat.

While Stan, Dipper, Mabel and Soos are falling in a bottomless pit, they tell stories to pass the time.

Li'l Gideon swindles the Mystery Shack away, forcing Grunkle Stan and the kids to move in with Soos. While Stan weighs how he can still care for his grandniece and nephew, they decide to take on Gideon.