million. Dolores places helmets on the heads of the captives, wired to a control board where she can electrocute them. Despite receiving the ransom money, she still decides to kill the captives. Superman throws a huge stalagmite into the switchboard, breaking the electrical connection, and tries to capture Dolores. She waves a lighted torch in front of the captives and Superman, seeing the mad look in her eyes, realizes she is Ultra. After Superman extinguishes the torch, Dolores dives into the water and escapes. Soon after, the Ultra-Humanite reads of the discovery of an atomic weapon created by physicist Terry Curtis. As Dolores, the villain seduces and kidnaps the scientist. After extended torture, Curtis agrees to help the Ultra-Humanite build an atomic arsenal. The Ultra-Humanite tells the city she wants $2 million or she will destroy every building and life in the city. As a demonstration, she promises to destroy the Wentworth Tower that afternoon. When an airship attacks the Tower, Superman holds the Tower up long enough to let the spectators escape. Superman destroys the disintegrator and follows the plane to the criminal lair, which is a city inside a volcano, and defeats the robot guards. Inside, the villain threatens to destroy Metropolis if Superman moves closer. In exchange for the release of Curtis, the Ultra-Humanite sends Superman to steal crown jewels, expecting him to be destroyed by the guards as she alerts them. Superman is able to battle past the guards and get the jewels. When Superman returns with the jewels, the Ultra-Humanite sends diamond drills at Superman, but Superman breaks past them. Curtis stops Ultra from pulling the lever that will destroy the city. Superman then disintegrates the photoelectric cell connections. Confronted again with her ultimate foe, the Ultra-Humanite dives to her apparent doom in the volcano's crater. The Ultra-Humanite made his last Superman appearance in Action Comics #21 (1940), where he apparently dies, and made no further comic book appearances for several decades. He was subsequently replaced as Superman's archvillan by Lex Luthor who would be introduced in Action Comics #23 (1940). Silver Age and the Multiverse With the introduction of DC's multiverse system, the continuity of Golden Age Superman stories and the Ultra-Humanite were retroactively placed on Earth-Two, the Earth of DC's Golden Age characters. The Ultra-Humanite was reintroduced during the Silver Age as a recurring villain in the "Mr. and Mrs. Superman" feature in