Shennan and Adin are two minds joined in a single body, one of the rare Bound. Bred and trained as an elite soldier, they protect the Polis's clandestine First Contact Teams on new worlds. The Bound can be reanimated into a new body after death, and brutal deaths on hostile worlds are a price they willingly pay to protect the Polis. On Polis worlds, violence is long forgotten; equity and justice are universal. But when peaceful citizens transform into savage killers—the Mad—idyllic Polis worlds descend into chaos. The Mad are spreading. The Mad are winning. And the Mad know how to kill the Bound—permanently. Shennan and Adin become the key to destroying the source of the Mad. Thrown into a frantic pursuit from star to star, they will be tried not merely in battle but in their hearts. Will friends abandon them in horror at what they must do? Can they defeat the Mad without becoming a monster?