After the events of Gravity Falls, Bill Cipher escapes death and grants him a second chance to live. A few years later, he was found by a high school boy named AJ, where both of their lives have been changed. Meanwhile, an old friend of AJ's tries to stop Bill Cipher from conquering the world, along with dealing with his new servant: The Believer, also known as, Darth Craidos.

Eria was your normal teenage viking girl, her family, respectable, her life easy, her love life, amazing. ah, to be bethrothed to one brother but you love the other. but things all change after Eria has to kill her first dragon. leaving both her lover and her self worth alone, now, 15 years later, they meet again, this time on different sides. Two side to the same coin. (I don't see to much Httyd book now a days so :P)