Everything about Anna's life is a secret. Her father works for the Branch at the helm of its latest project: monitoring and administering treatments to the four genetically altered boys in the lab below their farmhouse. There's Nick, solemn and brooding; Cas, lighthearted and playful; Trev, smart and caring; and Sam . . . who's stolen Anna's heart. Reserved and always controlled, Sam does everything with purpose.

When the Branch decides it's time to take the boys, Sam stages an escape, killing the agents sent to retrieve them. Anna is torn between following Sam or staying behind in the safety of her everyday life. But her father pushes her to go, making Sam promise to keep her away from the Branch, at all costs. There's just one problem. Sam and the boys don't remember anything before living in the lab -- not even their true identities.

Now on the run, her father's warning in her head, Anna begins to doubt everything she thought she knew about herself. She soon discovers that she and Sam are connected in more ways than either of them expected. And if they're both going to survive, they must piece together the clues of their past before the Branch catches up to them and steals it all away.