When two children are shot by a 7-year-old boy, Mannion makes it his mission to find exactly how the boy got his hands on a gun.

When Mannion questions the 7-year-old, he learns that the youngster took the gun from his 15-year-old brother who reveals that he got the gun from a ""guy on the street"" near his school. With the help of Temple and Debreno, Mannion sets up a sting and discovers that the weapon was actually a gun that the police had confiscated in a ""buy-back"" program. Now, with the Public Safety Commission breathing down Mannion's neck, he must track down the culprits before any more guns hit the street or any more children get hurt.

After beloved Ella Farmer dies unexpectedly, all the members of the police district pay a tribute to her, remembering all the hard work and effort she put in her job. They pray together and miss her, knowing she'll be forever in their heart, and that no one can ever replace her as Mannion's right arm.