The team attend at the apparent suicide of student Jason Renfrew at the local university. The Dean tells Leo Jason complained to her about racist bullying and he is found to have swallowed a chip containing photos of the alleged bullies, as well as having a handgun in his locker. Soon afterwards a gunman goes on the rampage, killing several people including the policeman investigating Jason's death. Nikki and Harry are trapped in a classroom with some students, one of whom, the mortally wounded Matt Frisk, was one of Jason's tormentors. Commander Somerville leads the police team who release them though it is Harry who finds the severely injured gunman. However, he fails to spot the bomb planted on campus.

Harry suspects that Scott Weston, the injured gunman, was shot by another person and it becomes obvious that two guns were used in the massacre. Scott's mother tells Dean Mears that Scott and Jason were good friends, Scott looking out for the more fragile Jason. Meanwhile Nikki is held prisoner in the deserted mortuary by unbalanced Neil Corrigan, who appears to have planned the massacre with Jason - who chickened out and killed himself - and then framed Scott. Ultimately video evidence reveals what actually happened, as well as locating the bomb.

When an ex-convict is found murdered in his home suspicion falls on a recently released child killer. Both men are clients of forensic psychologist Sasha Blackburn, whose work with the men is called into question.