The town of Gravity Falls, or at least the woods nearby, is filled with weird stuff.
Some of it has a logical explanation.
Apparently, it’s Family Fun Day and Grunkle Stan wants to take Dipper and Mabel somewhere. Where? Who can say? He isn’t. Hopefully it goes better than their last outing which seemed to be Stan having the kids hand-draw counterfeit currency. They got caught.
Stan has the kids blindfolded as he drives them to wherever. Stan’s not blindfolded himself but with his cataracts he might as well be. And then the Pines arrive for…the first day of fishing season. Yes, Stan wants to spend the next ten hours sitting in a small, rickety boat, telling bad jokes, and maybe catching a fish. Dipper and Mabel had other ideas involving a weird photo contest (the photo’s content would be weird, not the contest, but I suppose the contest could also be weird) with a $1,000 cash prize the twins would split. Dipper seems more interested in the fame and adventure of the contest, while Mabel would use her half to buy a human-sized hamster ball. It takes so little and yet so much to please that girl.
Point is, sitting in leaky boat with Stan probably isn’t going to win them any contests.
But then a miracle occurs. Two if you count Soos showing up with a much nicer boat, but the main miracle is the form of crazy old man Old Man McGucket. Looking and sounding like an 1890s prospector minus the desire for mining, Old Man McGucket talks about the giant Gobblewonker, this big thing with a neck like a giraffe and wrinkly skin like Stan that lives on a nearby island. So, the twins can have an exciting adventure looking for a monster on Soos’s boat, or they can fish with Stan.
They choose the monster hunt.
The island is creepy. Dipper brought plenty of cameras that the trio keep losing. A possum steals their only lantern. And the shape and roaring sound coming from a lagoon sounds promising, but the shape turns out to be a deformed beaver dam inhabited by beavers that just love to hug each other, and the roaring is a beaver chewing on a rusty chainsaw. You just can’t trust beavers.
And then the Gobblewonker surfaces and chases down Soos and the twins. Only a quick drive into a cave behind a waterfall as mentioned in Dipper’s book saves them when the beast gets stuck in the entrance.
And then Dipper sees the door. Yeah, it turns out Old Man McGucket built the thing because he was hurt his son (the guy who runs the local bait shop) doesn’t want to spend time with him, and it turns out Old Man McGucket builds giant robot monsters whenever a loved one hurts his feelings in any way. He may be crazier than anyone thought. I mean, we’ve seen this ending a million times on Scooby Doo and McGucket isn’t even trying to scare people away from his criminal enterprises.
But there’s a lessons there about spending time with family, so the kids go back to Stan and Dipper ends up losing his last camera anyway.
Besides, that thing swishing through the lake at the end might have been a real Gobblewonker. Those can be dangerous.