Monster

Alex and Trinity Heartwaters' parents decided to send them off to stay with their Grunkel Stan in Gravity Falls for the summer along with their cousins Dipper and Mabel Pines. But something happens that changes Alex's and Trinity's lives forever.

Gravity Falls does not being to me

BTW, this starts at the beginning of Dipper and Mabel's first summer in gravity falls

Sorry I'm bad at summaries.