The Sin Factor - DC Bad Boys Series, #1

In this intriguing mystery, Jeffrey Sinclair has a thief in his midst. One of his highly sensitive prototypes has gone missing and in his search, he finds himself in the middle of a deadly game, where trust is a luxury he can't afford. The last person to have the devices has been killed, and now, his only link to the stolen property is the man's widow. Avery Montgomery is a woman heroes marry and protect for life, but Sin's never been the protective, hero type--not like her late husband.
When her life is put in danger, Jeffrey must follow the twists and turns to uncover the truth before it's too late. It doesn't take him long to realize he wants the impossible...to be her hero.