Altered (Altered, 1)

They were made to forget. But they'll never forgive.
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, light-hearted and playful; Trev, smart and caring; and Sam . . . who's stolen Anna's heart.

When the Branch decides it's time to take the boys, Sam stages an escape. Anna's father pushes her to go with them, making Sam promise to keep her away from the Branch, at all costs.
On the run, with 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.