Finn Callaghan’s quest to prove his father wasn’t dirty and to follow family tradition leads him to become one of Boston’s brave. Like his father and brothers, he proudly wears the blue but as an openly gay man. His first assignment—going undercover as a teenage runaway. The sexy detective in charge is a bonus and a distraction he just can’t pass up. Only half out of the closet, Michael Caruso heads a task force to end an underage prostitution ring that preys on homeless gay teens. He has mixed emotions about using the hot young rookie as bait. Finn is perfect for the part, but Michael’s attraction to the pretty cop might botch months of work. Attraction turns to alarm as Finn goes deeper undercover. Can Michael keep him safe? And even if he can, how can he protect himself from the danger falling in love?

After the deaths of his parents and having to raise his younger brother, Detective Ronan Callaghan looks for three things—a good time, his next case, and when time allows, the man who murdered his family. The jury is still out on his new partner, but the hot new medical examiner at the first crime scene they share does it for him hands down. Diego Nieves hopes his new job in Boston will allow him to shake the painful memories of an on-duty shooting. Haunted by the event, he takes his job seriously and isn’t certain he can work with a cavalier partner. He sure as hell wants to work more closely with the pretty ME standing over his first homicide vic. Newly free from a long and boring engagement, medical examiner Cassidy Barnes is finally free to cut loose with her sex life. She’s determined to break old patterns and start taking new chances. When two sexy cops catch her eye, she can’t resist either—the charming rogue or the serious romantic. Just when Ronan and Diego begin to click as partners, their simultaneous relationship with Cassidy pits them as rivals. As each man vies for her attention, Cassidy struggles to choose between them. Solving the case and keeping Cassidy just might mean Ronan and Diego must to learn to work together…in more ways than one.

Regan Malloy is a dedicated homicide detective married to her job. A tough woman who holds her own when it comes to the opposite sex, she is nevertheless resigned to lonely nights with fantasy men. When a serial killer targets wealthy submissive men from an upscale BDSM club, Regan is convinced the killer is a woman and goes undercover. Kyle Ramsey is a topnotch litigator juggling life as a divorced father and a workaholic. Raised to be strong and to always take charge, he has trouble trusting that anyone else can get the job done. When he finds his good friend murdered, he mounts his own investigation despite Regan's warning not to interfere. Regan is furious to find the sexy lawyer at the club but can't deny her attraction or her need to dominate him. Kyle discovers more than clues as, to keep from blowing their cover, the fiery cop demands obedience. Together they embark on a journey to explore this new world of hidden desires, but the road could take a dangerous turn when they cross paths with the killer.

As the oldest of the Callaghan brothers, Daire held his family together when his parents were murdered. With his brothers finally grown, he is able to truly deal with his loss—and his loneliness. But he's out of practice when it comes to dating so he buries himself in his new position as police lieutenant. Parker Li works in internal affairs. Having experienced bad cops, she strives to weed them out. Proud of her Chinese heritage and her mission, she refuses to be intimidated by the hostility she encounters. She has also put her personal life on hold, unwilling to settle down with the guy of her family’s choosing. When Parker stumbles upon the Callaghan file and reopens the case, Daire is, at first, dubious about the sexy dynamo who pushes her way into his office and his life. But while her dedication wins him over, Parker resists the temptation of the steamy lieutenant with the chip on his shoulder. The case is cold, but heat rises as they face the growing desire between them and the danger of solving the murders.