Heavenfire

A divine sword, magic tomes, and uncontrolled power. Can 16-year-old Ginny Gracehurst keep them from an obsessed half-demon?
After retrieving the only thing that could set Jacob's demon father free, half-angel Ginny has a new mission. She and Aiden are charged with collecting the Eternal Tomes, which teach how to use sigils in the Angelic Tongue.
They are in a race against Jacob and his minions, who can travel anywhere in a matter of seconds. Allowing demonkind to learn those sigils would spell disaster for them all. In order to get what he wants, Jacob needs one more thing besides the Tomes-Ginny herself.