The Phantom Empire: Chapter 03 - The Lightning Chamber on AllMovie

Both Frankie (Frankie Darro) and Betsy (Betsy Ross King) manage to parachute to safety. Meanwhile, 25,000 feet below the surface, in Murania, Queen Tika (Dorothy Christy) sentences the captain of the Thunder Riders (Ray Bernard, later known as Ray "Crash" Corrigan) to death in The Lightning Chamber for failing to catch Gene Autry and thus prevent the continuation of the Radio Ranch, whose popularity threatens to expose the secret underground empire. But the captain, Ord, is spared by Argo (Wheeler Oakman), Murania's Lord High Chancellor, who is secretly planning to overthrow the queen. Back at the ranch, an incognito Gene comes across the rifle that killed his partner, Baxter, but Professor Beetson (J. Frank Glendon) and his thugs are right behind. Discovering too late that his getaway car is missing the brakes, Gene crashes over a steep cliff.