Wren is still reeling from the revelation that the mother she thought was dead is actually the Corpse Queen, a ghostsmith with the terrifying power to control the undead. It was Wren's own mother who created the iron revenants--an army of near unbeatable undead soldiers. When the iron revenants attack, no one in the Dominions will have the strength to stand in their way.

Now Wren, Leo, and Julian find themselves once more in the Breach, this time on the run from Wren's father, who is determined to secure more power for himself and the House of Bone. The three are desperate to stop the upcoming war, but working together is easier said than done with Julian still furious about Wren double-crossing him. And to make matters worse, Wren is plagued by powerful new abilities that force her to reassess everything she knows about being a bonesmith.

When Wren's long-lost twin brother shows up and vows to help her destroy the well of magic that feeds the iron revenants, she must decide if trusting him is worth potentially playing right into their mother's hands.

After all, the dead might be dangerous, but it's the living who can betray you.