There are some things in life that will bond you as friends. For Detective Billie McCoy, surviving a kidnapping and sex-slavery ring with two ex-prostitutes and a drug trafficker is one of them. Naturally, once the girls were home safe, Billie used her connections to help Sarah, Casey and Jane find their dream jobs on the right side of the law. But she soon learns she can't protect them from the past, and it's not long before an old flame of Sarah's comes knocking, wanting his best girls back in the game.

Sarah declines his offer, but in doing so sets off a chain reaction that lands Billie in hot water. Framed for drug use and possession, Billie learns the drugs are related to a much larger drug syndicate, one that is entrenched in the prison system. Billie and the girls form an agreement with the police; they go in undercover to bring their attacker to justice. It's a risky operation. The last undercover cop to enter the system was found dead just three days later. The girls begin to gather their evidence, working together as inmates. But when Billie is exposed, their mission suddenly turns to one of survival. Billie becomes a new target and her enemy is desperate to eliminate her. Can she survive the inmates' onslaught? Can she get the evidence she needs before it's too late? Even with her friends' support, they will need each other more than ever to walk out with their lives.