Beyond the moon lies the Planet Emperor. This is the assumption on which this science fantasy is based. It is to this world, a young English lad travels, in the company of the visionary Julian Harvey and a crew of convicts escaped from Dartmoor prison. There's a trip through space before they reach Emperor, which in certain seasons is subject to contamination by volcanic gases, but at other times offers the earth great resources, and it is the exploration of these facts that occupy most of the story. Relationships between the boy and the older men add a dimension to what would otherwise be a fairly routine projection of man into outer space.