Release Me by Aria Grayson

A man who can’t afford to lose control—and a man taking control for the first time…

Tom used to fight his way through life in a haze of rage and self-destruction, until his time in the army taught him the discipline he needed. Since then, he’s kept his passions on a tight leash, afraid of what would happen if his old anger broke through again. But once he finds out that the daughter he’s never even had the chance to meet is in danger, he doesn’t know if he can hold back anymore.
Raised in the brutal world of the Syndicate, gentle Callum has been told his whole life that he doesn’t have what it takes. After failing yet another job for his father, he’s given one last chance to prove himself—but when he discovers that it involves a kidnapped child, he risks his life to defy his family and save her.

On the run together, united by their determination to keep Tom’s daughter safe, they soon learn that it will take all Tom’s military training and all Callum’s inside knowledge to stay one step ahead of the Syndicate. But as the attraction between them grows, they discover that the greatest threats come from within. In admitting his feelings for Tom, Callum is forced to confront a side of himself he’s kept locked away all his life. And Tom must learn how to let himself feel again without giving in to his old demons—before the rage inside him puts them all at risk.