Mac investigates the shooting of a 14-year-old boy, while he and his younger 12-year-old brother walked home from school. Since the younger brother is the only witness, he points out who did it. However, the suspect can only be charged with stealing the boy's watch, and no evidence points to him committing the shooting. As Flack becomes personally involved in the case, the CSIs learn that the brothers robbed a bank to help their mother pay the rent, and it was the another suspect who did the shooting.