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After being transported to Mars, Ulysses Paxton becomes the assistant to Ras Thavas, the greatest scientist of Mars. Ulysses, now called Vad Varo falls in love with young Valla Dia, and after she has a brain exchange with an old empress, Xara, vows to re-unite her body and brain.

"The Master Mind of Mars" was first published in Amazing Stories Annual (July 15, 1927). The first hardcover edition was published by A.C. McClurg & Co., March 10, 1928. The dust jacket, title page drawing and five interior plates were done by J. Allen St. John.