Prolouge

Danny Fenton and his family go for a week long vacation to visit cousins in Gravity Falls Oregon. Danny expects a break from ghost fighting, but soon realizes that there's more going on in the town than anyone can see.
With the help of Dipper and Mabel, they begin to expose the ghostly side of Gravity Falls. And they find more than they wanted to.

Timeline: Before "Phantom Planet" for Danny, and after "Dungeons, Dungeons, and more Dungeons" for Dipper.