Lieutenant Commander Harm Rabb, Jr. is back to prosecute all crimes, accidents, and espionage related to the Navy and Marine Corps. He and his partner, Major Sarah "Mac" MacKenzie, use their wits to solve the mysteries behind the cases. In this season, cases aboard carriers, submarines, and even a hijacked plane demand their attention. And as Admiral Chegwidden finds romance, and Bud and Harriet adjust to parenthood, the whole gang travels to Australia.