The Flood Circle — Harry Connolly

The three original spellbooks, source of all magic in the world, have been found, and Ray Lilly has already acquired one. Now he and Annalise are on a historic mission to get the other two and they're ready to kill anyone who gets in their way.If they succeed, the Twenty Palace Society will become more powerful than it has ever been and could truly safeguard humanity from both extra-dimensional predators and the people who summon them.But this time their enemies are more formidable than any they've ever faced before. What starts as a covert mission to hunt sorcerers quickly collapses into a desperate—and very public—struggle to survive. Can Ray and Annalise track down and kill these sorcerers before they execute a plan to drive the human race to the edge of extinction?