The Lock (Dark Path Series #3). The Dark Path, #4

Erika Walsh's every dream has come true. She's received both critical and public acclaim for her best-selling erotic romance, and has chosen the magnetic millionaire and BDSM club owner Maxwell Crawford as the keeper of her heart. Although, her former crush Chris Milton still refuses to accept her decision. As she plans her wedding to Max, she's confronted with his past and the many secrets he's kept under lock and key -for good reason.
When Max's older brother, Daniel, a big Hollywood producer falls ill, Erika and Max rush to Los Angeles to help him recover. Max is shocked to find Daniel has become the victim of a blackmailer who seeks revenge against the brothers. Max must confront the loathsome Abraham Rovner, a former classmate from high school, who has never forgiven him for breaking off their relationship. Abraham brings out Max's lurking deviant nature, which sends him to a dark place in his mind.
Erika must find the strength to help her lover purge his demons, even though it may come at a major cost for them both.