"Cas Russel has decided to Fight Crime. 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 crime...