Jeremy Clyde is a young scientist who discovers that Time is a circle, and that deep within the human brain is a memory 'hangover' of future and past events. He carries out an experiment on himself and succeeds in mentally projecting his body 2,000 years into the future. Here he learns that his arrival in 3950 has been anticipated, and incredibly, he is appointed as the nominal ruler of the four inhabited inner planets, Mercury, Venus, Earth and Mars. But he discovers he is only a puppet for a ruthless governing system being secretly maintained by malign Jovians. Clyde joins forces with his counterparts on the three other planets and battles to throw off the alien yoke...