Frey, Ovie, Juniper, and Runa are the Boneless Mercies—girls hired to kill quickly, quietly, and mercifully. But Frey is weary of the death trade and, having been raised on the heroic sagas of her people, dreams of a bigger life.

When she hears of an unstoppable monster ravaging a nearby town, Frey decides this is the Mercies' one chance out. The fame and fortune of bringing down such a beast would ensure a new future for all the Mercies. In fact, her actions may change the story arc of women everywhere.