Empire (Monster Falls Book 2)
It's been four years since the events of Kidnapped and Mabel Pines is now turning 17 - also she's ALWAYS in trouble (and still very much human). After leaving Gravity Falls without her brother, Mabel is prepared to face another birthday by herself, however this year will be different. She may lack a certain twin, but she still has her guardian Will Cipher. Cipher has his doubts over Mabel's plans to return to Gravity Falls but with tension rising between the two of them, he feels compelled to follow her.
Well - that goes well. Reunited, Mabel and the monsters uncover some dark secrets from the Cipher brothers' past that just won't rest...