The Savior by JR Ward

In the venerable history of the Black Dagger Brotherhood, only one male has ever been expelled—but Murhder’s insanity gave the Brothers no choice. Haunted by visions of a female he could not save, he nonetheless returns to Caldwell on a mission to right the wrong that ruined him. However, he is not prepared for what he must face in his quest for redemption.

Dr. Sarah Watkins, researcher at a biomedical firm, is struggling with the loss of her fellow scientist fiancé. When the FBI starts asking about his death, she questions what really happened and soon learns the terrible truth: Her firm is conducting inhumane experiments in secret and the man she thought she knew and loved was involved in the torture…. Read more.