Unmade by Midnight (The Pact Trilogy Book 1)

For 300 years, one treaty has kept Boston's vampire clan and witch coven apart. Devi Grail is the wall. As the coven's Wardmaker, she raises the boundary that holds the two peoples apart, and her craft is the only thing on earth that can kill a vampire. So when her wards begin failing from the inside, the clan sends the one being sworn to the same peace she is: August Crane, the vampire enforcer.