When Lt. Austin receives a strange fax of the itinerary for someone called “Sheppard,” she and Commander Rabb don’t realize the seriousness of this fax. Later, Austin is shot and critically injured while at JAG headquarters by the person who accidentally sent the important fax to the wrong number. Rabb learns the shooter must be the infamous assassin known as “Hemlock;” a person that no one has seen long enough to give a description. Now, Rabb must find out Sheppard's true identity in order to find the assassin before he strikes again.