Her code name is Sparta. Her beauty veils a mysterious past and abilities of superhuman dimension—the product of advanced technology. Much excitement has arisen throughout the galaxy over the exploration mission to Jupiter's moon, Amalthea. Led by the renowned Professor J.Q.R. Forster, the dangerous expedition will lead its members to the surface of this strange moon—and beyond. It is Sparta's mission to monitor the trip on the part of the Board of Space Control. Her task becomes more threatening when Sir Randolph Mays, Forster's rival and nemesis, "accidentally" crash-lands on Amelthea's surface. Far from innocent, Mays has a plan for laying claim to Forster's discoveries, and only Sparta is able to prevent sabotage. But what is Mays really after? And how will they all react to the discovery of an alien life-form...?