Gravity Falls - A new Summer of Mysteries. Part 1 - Under Strings

After 3 years since the troubles of the weirdmagedon, Dipper and Mabel return to the City of Gravity Falls, trying to get some time to refresh their minds from the troubles that Teenage brought to them in Piedmont.
However, Gravity Falls is not a normal place, and new Troubles; more dangerous than the ones from the past seems to be happening around the town. The weirdmagedon was not the end for the weirdness this city have, and Bill was not the only interdimensional creature trying to take over the world.
In this part you'll see the Mystery twins getting back at the town after a whole lot of family troubles. New visitors came around to the town and they seem to be special as our Twins are.
Robbie seem to be up to no good, and the worts of all, the broke up with Tambry and now he's after Wendy once again.