Gravity Falls Season 2 Episode 17
Overview
Mabel makes plans for her and Dipper’s 13th birthday party; Dipper ventures below the town and discovers its most shocking secret.
Director: Stephen Sandoval
Guest Star: Alex Hirsch, Carl Faruolo, J.K. Simmons, Justin Roiland, Matt Chapman, Mike Rianda, Niki Yang, T.J. Miller