Night Broken by Patricia Briggs

#1 New York Times bestselling author Patricia Briggs’s Mercy Thompson series has been hailed as “one of the best” (Library Journal). Now Mercy must deal with an unwanted guest—one that brings a danger unlike anything she’s ever known.

When her mate’s ex-wife storms back into their lives, Mercy knows something isn’t right. Christy has the furthest thing from good intentions—she wants Adam back, and she’s willing to do whatever it takes to get him, including turning the pack against Mercy.
Mercy isn’t about to step down without a fight, but there’s a more dangerous threat circling. As the bodies start piling up, she must put her personal troubles aside to face a creature with the power to tear her whole world apart.