When D.S. Roach's case against Mickey Owen, a protection racketeer, is thrown out of court, Roach comes under pressure from the Flying Squad to convince Roxanne, a transvestite informant, to give evidence against Owen. Roach is reluctant, as Roxanne was badly beaten when he failed to protect her the last time she gave evidence. In spite of this, Roxanne finally agrees to testify, considering she has nothing left to lose.