Dangerously His by Anna J. Stewart

She’s blurring the line between duty and desire.

After Javi Perez left ATF in disgrace — shattering her heart and almost destroying her career along with his — Agent Regan McKenna hoped to never see him again. She’s thrown, if not entirely surprised, to find him working for the mobster she’s gone undercover to expose. Posing as Javi’s lover is all too easy, but she has no plans to be honest with him about her mission or her motives. Then a deadly confrontation forces her to trust him, prompting him to reveal why he’s really there. And to admit that he’s never stopped wanting her.