Fifty years after Steve Stuart and his friends captured an alien starship, the Solar Union is a thriving interstellar power, while Earth is increasingly backwards and falling into barbarism. For two youngsters from Earth, the Solar Union offers the only chance they will ever have to make something of their lives ... But humanity's involvement in Galactic affairs has not gone unnoticed. The enigmatic masters of the universe have put together a fleet to crush the upstart humans before they can threaten the precarious balance of power. Pushed to the limits, the Solar Union must fight to defend its freedom - and the existence of the human race.