The Black Mamba - Detective Billie McCoy, #4

Blood is thicker than water, or so they say. For Detective Billie McCoy, blood doesn't come into it with her family. Her three best friends, Casey, Jane and Sarah, are like sisters to her, and with the four of them lacking any blood-relatives, you'd be hard pushed to find a tighter bunch. So, when Casey's long lost cousin Jill turns up out of the blue, Billie is thrilled for the girls to have found each other.
They welcome Jill into their group with open arms. But Billie's detective senses are itching when she comes across a police sketch of a robber who looks sickeningly like Jill. Is Jill everything she seems to be? Was her sudden visit really to reconnect with Casey, or does she have an ulterior motive? Billie's investigation leads her down a rabbit hole and into a whirlwind saga that finds her and the girls dealing with ruthless businessmen, criminals and illegal boxing tournaments.
In a twist of events, Billie finds herself forced to fight as a contestant in one of the boxing matches. Her friends' lives are on the line. She will need all her skills and training to conquer her opponent and outsmart the tyrant running the contests.