The investigation into the carjacking of a vehicle containing vials of a deadly virus leads the detectives on a search for the first person infected with the virus and a biochemist whose sinister motivations were driven by passion.

After Green goes undercover to gather evidence on the gun dealers who murdered two detectives during a buy-and-bust, McCoy is able to connect the hit men to the attorney who paid them to avenge the death of his gun-running stepson at the hands of the same detectives during a similar buy-and-bust several years earlier.