Original Airdate: April 22, 1989
While attending a nuclear scientists’ convention, Clark sees a prominent physicist being kidnapped by some strange looking people. He follows them to the top of a skyscraper, where they promptly vanish after walking through a wall into a spaceship. Having been stunned by a ray beam, Superboy cannot stop the ship from leaving, and when Clark and T.J. try to report the mysterious happenings to the police, the officer interviewing them thinks that they are both nuts. Meanwhile, the kidnappers turn out to be dangerous mutants from the 24th century Earth. Because the plutonium and other materials they need do not exist in their century, they have returned to the 20th century to force the physicist to help them build a atomic bomb. He refuses, but they insist they have ways to force him into submitting. Back on Earth, Clark and T.J., and Lana try to learn what has really happened to Professor Lipcott, resulting in T.J. being taken prisoner as well.
Guest cast: Skye Aubrey as Val, Bill Christie as Hol, Edgar Allen Poe IV as Adio, Jack Swanson as Professor Lipcott.