For better or curse.

That might as well have been the wedding vow of Elle Chance and her new husband, the ex-Warlock Hugh Marsh. For the couple has scarcely returned from their honeymoon when the ancient battle between Light and Shadow tears them apart.

As Elle devotes herself to her duties as the Oracle—who alone has the power to keep the dark designs of Shadow at bay—Marsh finds himself missing the excitement of his former life as a Warlock. So when Commissioner Willoughby of the London Metropolitan Police seeks his help in solving a magical mystery, Marsh is only too happy to oblige. But in doing so, Marsh loses his heart, literally.

In place of the flesh-and-blood organ is a clockwork device—a device that makes Marsh a kind of zombie. Nor is he the only one. A plague of clockwork zombies is afflicting London, sowing panic and whispers of revolution. Now Elle must join forces with her husband’s old friend the Nightwalker Loisa Belododia to track down Marsh’s heart and restore it to his chest before time runs out.