Southland - Season 4

John returns to duty after recuperating from back surgery and meets his new partner, Officer Jessica Tang, a tough and disciplined cop with her own set of baggage from working the streets. Lydia, whose new partner is Detective Ruben Robinson, can't seem to escape helping a former CI who seems unable to stay out of danger, Ben, Sammy and Dewey chase an armed man into an elementary school, and Ben bumps heads with an intense street cop whose cynical attitude is affecting their work.

Things are gonna change with Joel Rucker as the new captain. Lydia and Ruben investigate a convenience store murder, and Lydia uses her typical compassionate charm to collect facts on her suspect from an unassuming grandmother. Meanwhile, John and Jessica get to test their physical abilities when they're attacked on the street. Elsewhere, Sammy and Ben ride with a mistake-prone officer, but Ben is the one making mistakes... mistakes that earn him some notoriety.

It's Hood Day on the streets of Los Angeles, and Captain Rucker has the department playing hall monitors. Sammy lets old grudges die hard when he leaves a gang territory unattended, only to have a violent gang war erupt throughout the city. Ben's recent mistake continues to haunt him everywhere he goes. Ruben practices his speech for his daughter's Quinceañera in the midst of a murder investigation. Cooper and Tang investigate a robbery in a strict Orthodox Jewish home, leading Tang to reveal parts of her past.

Jessica goes the extra mile to assist a homeless war vet obtain an ID so he can be admitted into a shelter; Sammy is determined to save a dog after he accidentally shoots it in the leg; Lydia struggles with a serious personal matter while she and Ruben investigate the murder of a man who sheltered and aided women in need.

John tries to save a suicidal teen in a situation that hits extremely close to home. Sammy convinces a former addict to be an informant, with devastating consequences. Tang gets a visit from someone in her past. Lydia and Ruben investigate a supposed home invasion that appears to have been staged to cover up murder.

Sammy tries to make amends after the murder of a young man who agreed to testify in one of his cases. John and Tang find themselves babysitting a documentary film crew. Lydia is ordered to put on her uniform and serve as shift supervisor for the day, but the job could be more than her body is able to handle.

Things just go from bad to worse when Jessica is served legal papers in the morning and involved in a shooting in the evening. Sammy holds a grudge against Ben for not backing him up over drug evidence that may have been planted during an arrest. Lydia comes to a decision about her situation.

Lydia and Ruben investigate the death of a young nanny, but first they have to find the kids who were in her care. Ben tries to intervene in the life of a prostitute with a daughter, but his efforts only make things worse. And while Tang gets an update about the boy she shot, John still wants her to come clean about what really happened.

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.

It's the last day on patrol for Tang, as she prepares to move to another precinct as sergeant. But first she wants to tie up some loose ends on the beat. Lydia is pressured to make a decision about the extent of her police duties during the rest of her pregnancy. With Sammy recovering from injuries, Ben and Dewey are partnered together. But Ben is bent on tracking down the prostitute he's been trying to help and then getting her and her daughter away from the abusive pimp controlling their lives.