The first hint that Earthmen had that aliens had come to their planet was a catastrophic one. Suddenly, without warning, all the atomic weapons and fissionable material on Earth were blown up. Panic, death and chaos reigned for months before things began to get back under control. By that time reports were already coming in of five mysterious star-shaped cities scattered over the globe - huge areas of flickering light and awesome free energy, disorganizing to human senses and impregnable to attack. The aliens had built their bases on Earth. But were they only bases, or - something else?

Genre: Science Fiction