He was a spy who forgot what it means to be human. She was a child who knew nothing of the arts of spies.

During the 1970s, a clandestine American agency known as The Institute finds people who are prodigies, enhances their abilities - and turns them into spies. Adam Walker, the Institute's most decorated success story, is exceptional because he is a prodigy at everything - except understanding people. When a rogue genius creates a cutting-edge aircraft for the Soviets, The Institute sends Adam and aeronautics specialist Nathanial Hemmel to Paris to investigate. But their simple research mission is quickly thrown into chaos when Adam encounters an obstacle his training could not prepare him for: a silent, mysterious child.

Five-year-old Kelli Bertrand is clever, charming and vulnerable - and may hold the key to understanding the aircraft. But is she just a deadly distraction? Adam, Kelli, and Nathanial now must race across the globe, while a shadowy organization tracks them, led by the one man alive who might be as talented as Adam Walker. To survive, Adam must unravel the mystery of this new powerful aircraft, the tiny, abandoned child, and why he risked so much to steal them both.