Nell Crane has always been an outsider. In a city devastated by an epidemic, where survivors are all missing parts—an arm, a leg, an eye—her father is the famed scientist who created the biomechanical limbs everyone now uses. But Nell is the only one whose mechanical piece is on the inside: her heart. Since the childhood operation, she has ticked. Like a clock, like a bomb. As her community rebuilds, everyone is expected to contribute to the society’s good . . . but how can Nell live up to her father’s revolutionary idea when she has none of her own?

Then she finds a mannequin hand while salvaging on the beach—the first boy’s hand she’s ever held—and inspiration strikes. Can Nell build her own companion in a world that fears advanced technology? The deeper she sinks into this plan, the more she learns about her city—and her father, who is hiding secret experiments of his own.