Mysteries of Unexplored Worlds #3 (1957)

Jo, a young man camping near a lake, insists he’s seen a mermaid rising from the water and even heard her speak, but the elders of his group dismiss him as delusional. When they imprison him in a cave to prevent his "madness" from spreading, he escapes just before dawn, racing toward the reeds where he believes she will return. As his frantic search ends with his tracks vanishing at the lake’s edge, the elders are left staring at each other, uncertain whether he was truly mad—or if they were the ones who failed to believe.

In a fantastical realm reached through a purple light, a shy observatory worker named Bill Jones is unexpectedly crowned king and wins the heart of the radiant Queen MMMMM, whose affection is as sudden as her world’s strange customs. As he navigates battles, royal challenges, and the dizzying thrill of being adored, he finds himself caught between the glory of his alternate life and the quiet reality he’s returned to—only to discover that love and legacy may not be so easily left behind.

In a forgotten world beneath the Earth’s surface, surface dweller Sam Cullen stumbles into a hidden society that has adapted to extreme heat since the last Ice Age, where he encounters a mysterious woman named Evna and a doctor, Kural, who holds the key to surviving the searing environment. As Sam grapples with the reality of this subterranean realm, he finds himself caught between the ancient tribal law that demands punishment for intruders and the growing bond he forms with Evna and Kural.

Dr. Kyle Duran, skeptical of the glowing reports from the planet Tsarus, ventures there alone after growing suspicious of Major Latimer’s evasive answers about the planet’s atmosphere and the absence of space suits. Once on Tsarus, he discovers the shocking truth: Latimer is not human, but a sentient machine housing the mind of a long-dead explorer, and the planet’s inhabitants are similarly artificial beings sustained by chemical reactions rather than biology.

In a whimsical 1957 sci-fi tale, reclusive ham radio operator Johnny Smith forms an unexpected bond with Satura, a mysterious girl broadcasting from Saturn, sparking a romance that defies the stars. When Satura arrives on Earth for their long-awaited interplanetary date, the encounter takes a surprising turn that leaves Johnny stunned and the world abuzz.