A new threat has enshrouded the neon streets of Sin City, and it's going to take some familiar faces to stare it down. William Petersen and Jorja Fox return to the roles they made famous -- and to the crime drama that made CBS history -- in CSI: Vegas. Can they prevent the perpetrator from bringing down the whole CSI crime lab? Old friends meet new enemies -- and the latest forensic techniques -- in CSI: Vegas.