Superman is facing some elemental danger on the cover of Issue 145 (May 1961).
Lois’ sister Lucy Lane, who had been introduced the previous year in Superman’s Pal, Jimmy Olsen, and already become a regular supporting cast member there and in Superman’s Girlfriend, Lois Lane. Siegel, Swan and Kaye have her try to help her love starved sister in this story.
Lucy asks Jimmy Superman’s secret identity, and Jimmy decides to test Lois’ ability to keep a secret. He lies to her, and tells her it is noted science fiction writer Rock Stirling, clearly meant to be The Twilight Zone’s Rod Serling. Lois swears to keep the secret.
The remainder of the tale shows how bad she is at it. Lois talks about Superman being Rick Stirling in her sleep, next to a live microphone, to her dentist while under sedation, and finally on live television. Superman has to go into action to save Stirling from vengeful hoods.
Lois admits at the end of the story that she isn’t yet able to keep a secret.
Rick Sterling does return, in a story in Action Comics in the late 70s, along with other men accused of being Superman.
The cover story, by Bernstein and Plastino, is not bad. Pure alien action. Lois Lane and Clark Kent go to cover a new circus in Metropolis, which claims to have interplanetary performers. Although Lois, and the other patrons, see this as a simple theme, Superman realizes that it is true.
The ringmaster of the circus has come to force Superman to join his troupe, threatening to send out a plant monster to destroy Metropolis if he refuses. Superman figures out that the plant creature needs sunlight, and causes an eclipse, which paralyzes it. The circus packs up before Superman can tar and feather them.
Siegel, Swan and Moldoff craft a much loved puzzler in this issue. After writing a normal diary entry, Clark Kent goes to bed, waking up the next day.
He finds that the world has gone crazy. Perry White looks like a Bizarro, Streaky and Krypto behave as if they are the pets of Lois Lane and Jimmy Olsen. Lois is dating Mr. Mxyzptlk.
Lana Lang attacks Superman with the bottle city of Kandor. Luthor, Bizarro and Brainiac show up to save him.
The villains are happy to admit that they know his secret identity, they read it in the comic book.
The bottom half of the last page, printed upside down, points out that if the story opened the night of March 31st, then the events from the rest of the story took place on April Fool’s Day, and the whole story was a big April Fool’s joke.