After the success of their last several cases, the reputation of the SIU is growing and they have earned the attention of New York Cities top officials including high ranking members of the United State government. When a former Russian diplomate ends up dead the SIU team is called in for a particular reason. Suddenly, the team finds themselves being pawns in an international conspiracy involving Russian money laundering, CIA spooks and former KGB hitmen. Yolanda is back, but a rift has formed between her and Jimmy as he attempts to ostracize her during the case. Tarik questions Jimmy's violent methods. Darius and Internal Affairs meet in secret.

Yolanda and SIU throw themselves into solving Jimmy's case. Miriam works alongside SIU. Respect growing between them. They retrace their steps. They follow old leads. When left with the facts they can come with only one conclusion … SIU has a dirty cop. Now the four of them are isolated and have to work outside the system. Yolanda and Tarik follow a lead and find Darius with Argon. A final confrontation between Yolanda and Darius leaves the team with only more questions. All the while Jimmy's life hangs by a thread in the powerful season finale of Bronx SIU.

The team is still reeling from Jimmy being shot. But, now they have a witness they are hiding from everyone as the SIU team secretly work to solve Jimmy Blue's attempted assassination. Their first case is a mystery wrapped in a riddle as they hunt down a serial killer and sexual predator preying on innocent women. But, they have an even bigger threat looming in the shadows.

Tarik and Tessa are becoming leaders in their own right. The crime world is stirring, and SIU finds themselves in the middle of a war. Then, as luck would have it, they get a key piece of information linking Jimmy's shooting to Argon. Tarik and Han go head to head in a battle of wits to find Jimmy's killer and once the dust settles, no one will be the same.

The sins of SIU have come back to haunt them. A team member has been kidnapped by a highly intelligent vigilante. The Vigilante's motives become clear and has been plotting for a long time. As the Vigilante's master plan draws to its conclusion the question becomes will SIU join him in his crusade or will they stop him?

Jimmy is up and about and staying away from SIU. Miriam and Zakia continue to work the case against Argon, but Argon and Han are plotting, and their plans are unfolding. Darius and Argon continue their 'business' partnership with Darius' daughter held as a bargaining chip. The team is falling apart, but through it all they are still SIU.