Grainger's time of service was nearly up. Pilot of the marvel spaceship Hooded Swan, the strange double-mind that occupied his brain had pulled him out of difficulties that would have doomed anyone else. But now Grainger had been warned. This trip could be the end. Because nobody knew what a newly created reality meant in terms of physics and chemistry - nobody but that alien parasitic mentality and it knew one thing - that it could not survive that kind of flight. Yet the existence of the Hooded Swan might depend on exactly such a survival.