When multiple bombs incite terror in Las Vegas, the shockwaves reach far and wide. Former CSI head Gil Grissom responds to the call of duty while FBI Agent Catherine Willows rushes back to her old hunting grounds. In his final Vegas case, lead investigator D.B. Russell helps unravel the fiendish web of evidence. The case turns personal as seasoned pro Sara Sidle navigates her history with Grissom.