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.