Heart of a Dragon — David Niall Wilson

Donovan DeChance is a collector of ancient manuscripts and books, a practicing mage, and a private investigator. Over the span of a long life, he has gathered and archived the largest occult library in the world. When a local houngan begins meddling with powers she may not be able to control, a turf war breaks out between a motorcycle club known as The Dragons and a Latin street gang, Los Escorpiones-a war that threatens to open portals between worlds and destroy the city in the process. With his lover, Amethyst, his familiar, Cleo-an Egyptian Mau the size of a small bobcat-the dubious aid of a Mexican sorcerer named Martinez, and the budding gifts of a young artist named Salvatore, DeChance begins a race against time, magic, and almost certain death. The fate of the city rests on his success, and on the rare talent of a boy who walks in two worlds, and dreams of dragons.