ABC's police procedural follows officers navigating their roles within the Los Angeles Police Department, with a focus on those early in their careers. In Season 8's finale, rookie Miles Penn faced a difficult patrol involving a station shootout, but his supervisor discovered he was not responsible for the incident and chose to accelerate his exit from the training programme rather than dismiss him.

Season 9 will feature Miles as a fully trained officer, no longer in probationary status. His advancement creates an opening for fresh recruits to join the Mid-Wilshire division, allowing the show to maintain its established format of following newcomers to the force whilst developing Miles into new storylines as an independent officer.