Superman #87

In "The Thing from 40,000 A.D.!", a mysterious protoplasmic entity descends upon Metropolis, capable of perfectly mimicking any form—including Superman’s own. As the creature assumes the guise of Earth’s mightiest hero, chaos erupts, forcing Superman to confront a chilling doppelgänger who wields his powers with sinister intent. Lois Lane and Perry White watch in disbelief as the city teeters on the edge of a crisis only the real Man of Steel can resolve.

After a string of near-disasters, Superman—ever the perfectionist—volunteers for a series of rigorous tests to prove his powers are still intact. With Lois Lane, Jimmy Olsen, Perry White, and the newly introduced Professor Vandyke all watching closely, even the ever-calm Cyrus Walters begins to wonder if the Man of Steel is slipping.

When a play dramatizing Superman’s battles with the Prankster arrives in Metropolis, the villain, furious at being portrayed as a joke, vows to turn the theater into his ultimate stage of revenge—right under the eyes of Lois Lane and Clark Kent, who are just trying to enjoy a night out.