After a mysterious shooting leaves one of their own injured, Bill and the team go out on a mission to find the shooter. Charlie attempts to get answers about what happened during the shooting, leading Joseph to a revelation. Meanwhile, when Undersheriff London tries to take control of the department, Bill reminds him who is in charge.

Charlie, Joseph and Carter investigate a case that becomes more complicated at every turn, while Bishop and Cade make a connection to a homicide they never expected. Still suffering flashbacks from the hospital takeover, Paula tries to find closure. Meanwhile, Bill's family strives to humanize him to the constituents of Los Angeles County

When informants for the Sherriff's Department start turning up dead all over Los Angeles, everyone has to work together to find the leak in the department. Meanwhile, Teresa and Cade deal with a major setback in the custody battle for their foster children. Also, on the day of Maggie's Quinceanera, Bill gets stuck in a difficult position between work and family in the season finale