The Dailey Planet newspaper sends mild-mannered Clark Kent and outspoken Lois Lane to the small town of Silsby to write a story about the nation's deepest oil well. Clark and Lois are accompanied by National Oil Company public relations representative John Craig and when they reach the well, they are surprised to find foreman Bill Corrigan dismantling it. Corrigan claims that after the home office ordered him to shut down the six mile deep well after receiving his most recent report. When Corrigan refuses to tell Clark what the report contained, the newspaperman's curiosity is piqued. Later at the oil well, night watchman Pop Shannon hears strange noises, but fails to see two odd small-bodied men emerge from a well opening. Soon after, Clark and Lois return to the well to investigate and find Pop dead in the company office. While Clark searches the grounds, the two strange subterranean creatures appear in the office window, causing Lois to shriek in horror. Later, Corrigan and the sheriff agree with the doctor's assumption that Pop died of a heart attack and that Lois' story of the men with "mole" bodies is a product of her imagination. Privately, however, Clark convinces Corrigan to reveal the contents of his report: When the company began drilling, Corrigan assumed that the glowing core samples found at 30,000 feet were radium, an intensely radioactive element known to be harmful to humans. At 32,600 feet, the drill broke through into mid-air and scrapings from the drill bit revealed living organisms. Clark believes these organisms may be evidence of advanced beings living under the earth's crust. When Corrigan claims that he put a metal cap on the well opening, Clark remembers that the cap was missing when he arrived earlier that evening. Meanwhile, the townspeople spot the molemen as they wander from the well into Silsby, causing everything they touch to glow along the way. Once they reach town, Ellen, a young child unafraid of the unknown, invites the molemen to toss her ball, which then begins to glow. Meanwhile, the alarmed townspeople gather at the Hotel Silsby to discuss the situation and Clark warns them that they must treat the creatures with care. When Ellen's mother sees the creatures, her shrieks interrupt the meeting, prompting townsman Luke Benson to incite the mob to violence. Concerned, Clark secretly changes his clothes and dons a blue and red suit with a red cape, the costume worn by his alter ego "Superman," a being from the planet Krypton who can fly and perform other super human feat. Superman advises the mother and child to go to the hospital for decontamination and then warns Lois that a newspaper story about the incident could lead to national panic. Using hounds to track the molemen, Benson and his men corner the creatures atop the town dam. When Weber, Benson's cohort, shoots a moleman, Superman arrives just in time to catch the creature before he falls into the reservoir and contaminates the water supply. Superman flies the creature to the local hospital, while Benson and his men continue to chase the remaining moleman. Exhausted, the frightened creature crawls into a small shack to hide, but Benson sets fire to shack to kill him. As the shack burns to the ground, the men believe the moleman is dead, however, he actually escapes under a loose floor board and hides in the brush. While the men return to town, the moleman rushes back to the mine and down the well opening. In town, the sheriff orders Benson to leave the remaining creature under Superman's care at the hospital. Benson then locks the sheriff and deputy in jail and leads the mob to the hospital. Inside the hospital, a young doctor risks radiation poisoning to operate on the wounded creature with Superman's assistance. After the surgery, the doctor reports to Clark and Lois that the creature's skeletal structure is remarkably similar to that of humans. After Superman has changed back to Clark, he spots the mob outside the hospital and leaves abruptly, prompting Lois to joke with Corrigan and Craig that Clark is a coward. Soon after, Superman returns to tell the mob that the moleman has the right to a peaceful existence and after deflecting bullets shot by one of the mob, wrestles their weapons from them. Meanwhile, the moleman has returned with a weapon, and approaches the hospital, flanked by two more molemen. When Superman appears, the escaped moleman gestures to the others that Superman saved their companion. Benson then points his gun in the direction of the molemen and they discharge their weapon at Benson, but Superman bravely steps in front of the gun's ray. Superman then fetches the wounded moleman and escorts the creatures back to the well opening after which they crawl underground. As Superman, Corrigan, Lois and others gather near the well, they see the glow of the weapon's ray and suddenly the entire well bursts into flames. After Superman pulls the humans to safety, Lois comments, "It is as if the creatures were saying, `You live your life and we'll live ours.'"
