Hodges presents the 'lab rats' with a series of hypothetical murders in order to give them a chance to play CSI.
Ray and Nick discover the corpse of a boy, and several body parts. Is Dr Jekyll back? Elsewhere, a dead woman is dumped in a hotel corridor.
The CSIs are called to a shoot-out at a gun store involving four people. Later, a separate murder is linked to the gunfight.
The apparent suicide of a freshman on a university campus brings Sara back in contact with an old nemesis.