The vector calculus blazing through Cas Russell's head lets her smash through men twice her size and dodge every bullet in a gunfight. In the first three books of her action-packed adventures, Cas faces opponents as powerful as telepaths and as unstoppable as mobsters. She's not the only person with a superpower or the technology to mimic one -- but how many can claim a mastery of the whole numerical world as their battle skill? Adrenaline, snark, and science fiction combine into a noir superhero thriller. This bundle contains the first three books, as well as two bonus short stories. BOOK 1 - ZERO SUM GAME Going up against a psychic with a god complex isn't exactly a rational move, but Cas isn't about to let anyone get away with violating her brain. Besides, she's got a small arsenal and some deadly mathematics on her side. There's only one problem . . . she doesn't know which of her thoughts are her own anymore. BOOK 2 - HALF LIFE Cas knows she isn't saving a child. She's only stealing a piece of technology that looks like one, and it's expensive and high-stakes enough that innocent people have already been killed over it. But Cas has a distraught father on one hand and a robot programmed to act like a distraught daughter on the other, and she's never been able to sit by when a kid is in trouble -- even a fake one. BOOK 3 - ROOT OF UNITY When Cas agrees to find a professor's stolen proof, she's immediately ducking car bombs and men with AKs -- this is the type of math people are willing to kill for, and the U.S. government wants it as much as the bad guys do. But all that pales compared to what Cas learns when she starts to unravel the mathematics. Because the more she works on the case, the more she realizes something is very, very wrong . . . with her. Bonus material: Short story - RIO ADOPTS A PUPPY A puppy appears on Rio's doorstep. Fortunately, Rio is fully aware he's a sadistic psychopath utterly lacking in empathy, and thus does not hurt the puppy. But he also doesn't know what to do with it. Bonus material: Short story - LADIES' DAY OUT Cas teaches Pilar to shoot. Considering Cas is an acerbic mercenary and Pilar is a delightful admin, this goes about how you'd expect.

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. She can take any job for the right price and shoot anyone who gets in her way.As far as she knows, she’s the only person around with a superpower . . . but then Cas 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 puppet master.Someone who’s already warped Cas’s thoughts once before, with her none the wiser.Cas should run. Going up against a psychic with a god complex isn’t exactly a rational move, and saving the world from a power-hungry telepath isn’t her responsibility. But she isn’t about to let anyone get away with violating her brain — and besides, she’s got a small arsenal and some deadly mathematics on her side. There’s only one problem . . .She doesn’t know which of her thoughts are her own anymore.

Cas Russell is back — and so is her deadly supermath. Cas may be an antisocial mercenary who uses her instant calculating skills to mow down enemies, but she’s trying hard to build up a handful of morals. So when she’s hired by an anguished father to rescue his kid from an evil tech conglomerate, it seems like the perfect job to use for ethics practice. Then she finds her client’s daughter . . . who is a robot. The researchers who own the ’bot will stop at nothing to get it back, but the kid’s just real enough for Cas to want to protect her — even though she knows she’s risking everything for a collection of metal and wires. But when the case blows up in her face, it plunges Cas into the crossfire of a massive, decades-long corporate espionage war. Cas knows logically that she isn’t saving a child. She’s stealing a piece of technology, one expensive and high-stakes enough that spiriting it away is going to get innocent people killed. But she has a distraught father on one hand and a robot programmed to act like a distraught daughter on the other, and she’s never been able to sit by when a kid is in trouble — even a fake one. Screw morals and ethics. All Cas wants to do is save one little girl.

Back for book three . . .Cas Russell has always used her superpowered mathematical skills to dodge snipers or take down enemies. Oh, yeah, and make as much money as possible on whatever unsavory gigs people will hire her for. But then one of her few friends asks a favor: help him track down a stolen math proof. One that, in the wrong hands, could crumble encryption protocols worldwide and utterly collapse global commerce.Cas is immediately ducking car bombs and men with AKs -- this is the type of math people are willing to kill for, and the U.S. government wants it as much as the bad guys do. But all that pales compared to what Cas learns from delving into the proof. Because the more she works on the case, the more she realizes something is very, very wrong . . . with her.For the first time, Cas questions her own bizarre mathematical abilities. How far they reach. How they tie into the pieces of herself that are broken -- or missing.How the new proof might knit her brain back together . . . while making her more powerful than she's ever imagined.Desperate to fix her fractured self, Cas dives into the tangled layers of higher mathematics, frantic for numerical power that might not even be possible -- and willing to do anything, betray anyone, to get it.