Ep 4. Brother's Keeper

Detective Andy Sipowicz is called to investigate a shooting incident at a night club where a young man was shot and killed. The victim's brother, a musician named Teddy, was present at the club during the shooting and becomes one of the prime suspects in the case. The investigation takes a complicated turn when Teddy's alibi falls through and evidence starts to pile up against him.

Meanwhile, Detective Bobby Simone is assigned to investigate a series of thefts at a high-end jewelry store. After conducting a thorough investigation, Bobby discovers that the store's security guard is the culprit behind the thefts. However, when the security guard is confronted, he claims that he was coerced into committing the crimes by an unknown person. Bobby must race against time to find out who the brain behind the thefts is and arrest them before they can commit any more crimes.

At the precinct, Lieutenant Fancy assigns newly promoted Detective Diane Russell to train another new detective, Jill Kirkendall. However, their working relationship gets off to a rocky start when Diane exhibits a condescending attitude towards Jill and undermines her authority in front of their colleagues. As the case progresses, Diane realizes that she was in the wrong and apologizes to Jill, and the two eventually work together to solve the case.

Back at the night club shooting investigation, Andy discovers that the victim's brother Teddy was involved in a drug deal gone wrong, leading to the murder. With the help of Detective Martinez, Andy is able to track down the drug dealer and make an arrest, effectively closing the case.

In the final scene of the episode, Bobby confronts the person behind the jewelry store thefts and discovers that it was actually the store's owner who masterminded the entire scheme. The owner confesses to the crimes and is subsequently arrested, handing Bobby a rare victory.