Ten years ago, Las Vegas was terrorized by CASt - a vicious serial killer responsible for nearly half a dozen brutal murders, and who tested the mettle of the LVPD's new Captain, Jim Brass. After a two year spree, CASt suddenly disappeared and has not been heard from... until now. Gil Grissom and his CSI team are called in to investigate a homicide that perfectly fits the notorious criminal's modus operandi. But all hell breaks loose when a reporter made famous by the original cases receives a letter from someone claiming to be CASt - and who says he has nothing to do with the latest slaying.

Now the CSI's must stop someone who may be a copycat killer from striking again... even as a murderer from the past continues to evade capture, and isn't taking too kindly to rivals...