Colt Clemmons is an agent in a specialized division within the Bureau of Investigation—one that hunts down not just mobsters, but also monsters.

For reasons that are kept top secret, Colt is the only person who can resist a siren's voice. But he's never had a chance to test this ability. The last siren left in the world mysteriously disappeared years ago.

Then one night, with a single word, she reveals herself. It seems too good to be true.

And it is. Because nothing about this siren—her past, her powers, or her purpose—is what it seems . . .