Unleashed — John Levitt

If it had been only an animal, even a smart one, there would have been no problem. Animals just want to be left alone: they don't plot revenge or possess agendas. But it was more than that -- it was psychotic. It killed just to kill, and it had an unquenchable hatred of Ifrits.

Mason is an enforcer, keeping magical practitioners on the straight and narrow, and he knows exactly how dead he'd be without his "dog," Louie. Louie's more than a canine -- he's an Ifrit, a faithful familiar who's proved time and time again that he's a man's best friend, if said man values staying alive.

But this time Louie's in the line of fire. Practitioners in San Francisco have been dabbling in magic far beyond their control. Now they've accidentally unleashed a monster into the world. It's mauling humans and killing any Ifrit it can find. Mason and Louie must track and collar it. But doing so will lead them to an evil darker -- and more subtle -- than any they have ever faced.