: His character takes a darker turn as he spirals into a drug addiction that jeopardizes his career and relationship with the team.

: For the first time, the original five rookies (Andy, Dov, Gail, Traci, and Chris) are now five-year veterans. Andy McNally takes on a mentoring role as a Training Officer for a new, eager, yet problematic rookie, Duncan Moore .

: Introduces Duncan Moore ; Oliver begins his tenure as Staff Sergeant.

: Oliver Shaw is promoted to Acting Staff Sergeant—a role he is initially reluctant to accept—replacing Frank Best. Major Character Arcs

: The fallout from the shooting; Andy and Dov handle a diner robbery while off-duty.