The Citadels were the pinnacle of law and order in the Empire. They served as centers for trade and kept the peace in thousands of solar systems for centuries. Fleeing the destruction of their own Universe, one of these mighty stations arrived in ours, taking position in the atmosphere of Saturn. The only survivors were two doctors and the multitude of AIs that ran the station. Looking to Earth to repopulate the Station, a young man is selected to become the new biological half of the Controlling AI named Pollux. In addition to becoming the human half of an ancient computer, he learns of a major problem on Earth.