World-renowned professor J.Q.R. Forster's expedition to Jupiter's moon has not proven uneventful. In a furious blaze of ice-geysers, the moon's surface rips off to reveal an ancient alien world-ship. But when the world-ship suddenly hurtles through space toward a black hole, the scheming Sir Randolph Mays and Sparta unwittingly head for their final battle through the eons in the midst of an ancient galactic civil war.