In a world teetering on the edge of chaos, Sienna Nealon is the unrelenting force keeping the worst of humanity in check. But after years of sacrificing everything-her freedom, her relationships, her very soul-to hunt metahuman criminals, the cost is catching up. As she delivers justice with a ferocity that borders on vengeance, Sienna grapples with a chilling truth: she may never escape the cage of her own making.