Ben finds himself heading down a slippery slope as he attempts to help the daughter of a prostitute, putting him in hot water with the woman's pimp. Lydia and Ruben (guest star Dorian Missick) investigate the murder of a gang-banger who may have been killed over a graffiti tag. Tang (special guest star Lucy Liu) faces more questions about her shooting of an innocent bystander, which could determine whether she gets promoted to sergeant.