Bob Langdon, a young Pony Express rider, is given an appointment to West Point, but is forced to leave the academy as the result of political intrigue stirred up by enemies of his friend, General George A. Custer. Bob returns to the west and is made a scout for Custer's 7th Cavalry. At the Battle of Little Big Horn, Custer sends Bob with a message for aid, and Bob becomes the only survivor of the battle.

A traitor is lurking somewhere aboard the USS Carolina, and Lt. Tom Randolph is determined to find the offender. First a revolutionary new piece of technology -- an electric firing device -- is sabotaged. Then one of the cruiser's crew is murdered. In order to catch the killer, the captain locks down the ship. With foreign dignitaries, corporate goons and even Tom's girlfriend, Betty, trapped on the vessel, there is no shortage of suspects.