"Cas Russell has decided to Fight Crime(TM). She definitely doesn't have a cape, and she's working on the whole morals issue, but she does have a real-life superpower: with her extraordinary mathematical ability, she can disarm bombs or outshoot an army. But Cas's own power also has a history, one she can't remember -- or control. One that's creeping into her mind and fracturing her sanity. . . just when she's gotten herself on the hit list of every...