Tensions mount as the manhunt for the missing shooter proves to be more difficult than expected. Terry is promoted to acting lieutenant, which he soon discovers comes with responsibilities more taxing than he anticipated.

As the city reels, newly appointed D.A. Mario Siletti promises justice. Meanwhile, the body of a young Chinese gang member found in an urban grow house leads Hildy into the dangerous world of drugs and gang politics.

Raffi fears Hildy's continued investigation of the grow house murder will blowback on a case of her own.

Terry and Hildy take a high-ranking officer into custody, while Suger faces a new and unexpected threat to Potrero. Meanwhile, Molk uncovers unsettling information about a potential prostitution ring.

In the season finale, Terry and Hildy are gloves-off as they race to close in on a murder suspect, while Fatty B lobbies to take Potrero in a new direction. The Trial of Dustin Maker reaches a climactic verdict.