Cas Russell is good at math. Scary good. The vector calculus blazing through her head lets her smash through armed men twice her size and dodge every bullet in a gunfight, and she'll take any job for the right price. As far as Cas knows, she's the only person around with a superpower...until she discovers someone with a power even more dangerous than her own. Someone who can reach directly into people's minds and twist their brains into Moebius strips. Someone intent on becoming the world's pupp...