by C. D. Moulton (Author)

The crew are called to a world where there seems to be outside influence. They find a gleaming marble city with some strange inconsistencies. It is soon obvious there is outside influence that could destroy the people s chances to advance.

Second part, they go to the planet the inyterlopers have based a colony of people on. they are interfering as badly with an evolving culture - or are they?