Love in the Shadows by Elaine Meece

Two FBI Agents—one promotion.

Special Agent Ellen Bennett and Special Agent Garrett Emerson detest one another especially after learning they’re both after the same promotion. He sees her as rigid and difficult. She considers him an arrogant charmer, but his charm is wasted on her. When they go undercover as newlyweds to expose a sex trafficking ring, they have to live under the same roof and make it work. Not only do their careers depend on it, the lives of others do as well.