Architect Carter Grady is constructing his most prized design-a family. Two years after marrying his deceased best friend's wife, Tori, he's ready to officially adopt her two sons, independent Daniel, twelve, and sweet five-year-old Nathan. All he needs to do is sign the legal paperwork. But a phone call changes everything.

A one-night stand from over a decade ago died in a freak accident and Carter now learns two things: the random stranger's name . . . and that they share a ten-year-old son, Francis. With adultlike affectations and a fondness for wearing bow ties, the exceedingly charming and fiercely intelligent boy is unlike other children. And he's biologically Carter's-a seemingly impossible dream.

Yet behind the ready smile, perfectly parted hair, and need to please, something's off with Francis. There's a cunning calculation behind his moves, an effortless talent for lying, and a dark curiosity about others' pain. But as Carter and Tori learn about the shocking conditions of Francis' isolated childhood, Carter is even more determined to do right by his son.

When "accidents" soon escalate, with Daniel and Nathan caught in the middle, Tori's budding suspicions and maternal paranoia grow. Could evil reside in the form of a little boy? And who-or what-have they invited into their home, their trust, their sense of safety?