For the first time since Caroline, Sonny is thinking marriage to Theresa, a doctor he's been seeing. (Bonham-Carter is fabulous in the role.)
But Theresa harbors a secret addiction to heroin, which becomes an issue when she has to spy on Sonny's files to maintain her secret.
Crockett ends up blamed for the fiasco, but manages to earn a shot at redemption, using his status as a tarnished cop to his advantage against drug dealer Wyatt.
But Theresa can not escape her addiction and overdoses on heroin. While she survives, Sonny realizes treatment needs to include moving away from him. In the end he sits as a lookout on another case, staring at the ring he never got to give her.