Detectives Briscoe and Green investigate when a masked schoolkid opens fire on classmates, killing four and wounding eleven. It soon becomes apparent that more than one child fits the profile of a youth capable of committing such violence. An e-mail sent by one of the students skews the investigation towards one particular youth with a violent history. But finding the perpetrator becomes a race against time when another e-mail arrives threatening more murders. E.A.D.A. McCoy goes head to head with Jamie Ross (Carey Lowell), who is acting as the teen's defense attorney, and who argues that the e-mail is inadmissible because it is privileged.