Hour of Need (Laws of Magic Series #6)

In the earth-shattering final book of the Laws of Magic series, Aubrey goes deep into the lair of his enemy in an attempt to save the world

Aubrey Fitzwilliam, renegade and traitor. Instead of clearing his name in Albion, Aubrey has chosen to pursue his enemy, Dr. Mordecai Tremaine, deep into the heart of enemy territory. What he uncovers in Dr. Tremaine's stronghold promises to change the course of the war and the future of humanity itself. A hideous combination of electrical science, golem manufacturing, and soul-shattering magic is bringing the world far closer to the edge of the abyss than anyone apart from Aubrey realizes. Alone, reviled, and hunted, this is Aubrey's last chance to save the world—for if he doesn't there might not be a world left to save.