Once Upon a Swine is the second chapter book based on Gravity Falls episodes, published on October 7, 2014. The book is a print adaptation of the episodes "The Time Traveler's Pig" and "Land Before Swine."
At the moment when Mabel wins Waddles the pig at the Mystery Fair, Dipper ruins his chance to impress Wendy. But when Dipper finds a way to travel back in time and changes his fate with Wendy, Mabel's fate also changes-for the worse. Will Dipper and Mabel tweak time so they both leave the fair a winner? Will Mabel ever share a slice of pizza with her beloved Waddles again? Then, when a prehistoric creature snatches up Waddles, it's up to the Gravity Falls gang to save him! Readers will love this 112-page chapter book filled with black-and-white art from the show.
The cover shows Mabel in a red sweater holding Waddles, Dipper, Stan, and Soos in a frightened stance, and Blendin Blandin hiding behind a pine tree. The shadow of a pterodactyl is visible casting over them. On the top left, the show title "Gravity Falls" with a small Disney logo visible above it. Below it is the book title that says "Once Upon A Swine" in mint letters.
- This book came out alongside Dipper's and Mabel's Guide to Mystery and Nonstop Fun!
- Along with Pining Away, it was the only Gravity Falls chapter book ever made.