Mabel and Dipper get sent to the world of Undertale. They both fall down Mt. Ebott, where they meet all the monsters. I wonder what's going to happen. A/N: This is my first book so I hope you all enjoy it. Anyways, I do not own Undertale, Gravity Falls, or any of the art. Also there might be a little cussing in this book but not really bad cussing.
8 parts