Cate Winter, at 34, is a wildly successful neuroscientist and entrepreneur who has invented a cure for Alzheimer's that will improve the lives of millions. On the verge of selling her biotech company for an obscene sum, she is also about to become very rich.

But Cate has a secret that keeps her deeply uneasy about everything she is and does: she grew up at the Cleckley Institute, a treatment facility for the rehabilitation of psychopathic children. And, as far as she knows, she is the institute's only success: all of her peers have become thwarted, maladjusted or even criminal adults.

Then Cate discovers the existence of another ex-patient and outlier who might prove that her success isn't a fluke. He has not only stayed out of jail, but he's made a mark in business and science. Though his identity is confidential, she breaks the rules and drops everything to track him down. And when she finds him, living under an assumed name in Baja California, she is immediately obsessed. Like her, he is driven and brilliant, an innovator willing to do what it takes to perfect a new energy technology that will stop global warming. Here, at last, is her mirror, her ultimate collaborator, the possible answer to the enigma of her nature.

But in the wake of a mysterious death, Cate can't avoid suspecting him. If he is involved, do his ends justify his means? Ruthless herself, she's about to find out whether there are any moral lines she won't cross.