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

Dipper and Mabel discover their seemingly cherubic new neighbor, Lil' Gideon, happens to be the town's adored psychic. But when Dipper convinces Mabel to go on a date with Gideon to question his authenticity, she soon learns that his cuteness can fade all too quickly.