Southland - Season 4 (2012)

Lydia finds out she's pregnant as she tracks down a 15 year old female killer, Sammy tries to come to the rescue of a dog that he accidentally shot, and Tang and Cooper try to help a homeless Marine.

John has an eventful shift on the day he receives his pin for 20 years of service, Sammy and Ben try to out-prank each other, and Lydia and Reuben suspect that a father may have killed his 30 year old son.

A documentary film crew accompanies Cooper and Tang on their shift, Ben suspects that Sammy may have planted evidence to help settle a score, and Lydia risks her pregnancy and takes a shift in the field.

Tang is involved in an accidental shooting on the day she is served with divorce papers, Sammy gives Ben the cold shoulder after his accusations, and Adams and Robinson investigate the death of a drug dealer.

Sherman tries to come to the rescue of a prostitute and her daughter who is also turning tricks, Cooper and Tang get a case that closely resembles Tang's shooting, and Adams and Robinson investigate the death of a pregnant nanny.

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 investigate the murder of a gang-banger who may have been killed over a graffiti tag. Tang faces more questions about her shooting of an innocent bystander, which could determine whether she gets promoted to sergeant.

Ben spends his shift trying to settle a personal score with a pimp, Tang has her last shift with Cooper before taking her promotion, and Lydia has a traumatic case on the day that she announces her pregnancy.