Danny and Jamie combine forces to convict a notorious drug lord, as Erin nervously awaits the Governor's selection for the new District Attorney. Also, Frank and his grandson, Joe Hill, face a difficult decision as they navigate their new and complicated family ties.

 Frank must decide whether the department can accommodate a request to remain in the field from Detective Allison Mulaney, a lauded cop who is wheelchair-bound after being wounded in the line of duty. Also, Erin is conflicted by the weight of her authority in the sentencing of a man guilty of vehicular homicide, Danny and Baez pursue a rideshare rapist and Jamie and Eddie team up to aid a fellow officer when his partner is shot on the job.