E.C. Tubb 
Incident on Ath [EPUB ebook] 
The Dumarest Saga Book 18

The Painting was dramatic, passionate, a work of genius. But Earl Dumarest was blind to its power.For there, in the background, were the features of cratered Luna, satellite of Earth, the fabled planet that Dumarest had sought through countless galaxies.Dumarest had to find the artist, had to talk to him. His trail led to Ath – and to the ominous forces of the Cyclan.(First published 1978)