Surpirse

All is normal in Gravity Falls until Bill smashes an orb which pulls Mabel and him into another dimension, forcing them to work together to find their way back to Earth.
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UPDATE February 7, 2015: There is a sequel to this book! It is called "Gravity Rises".
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Edit: When I wrote this I knew nothing about the Will Cipher everyone knows about. He is nothing like the Will you know about!