Moon of Three Rings is by the prolific author who can generally be counted on to do multiple rings around any of the others working in the juvenile science fiction form, and this is one of her best. Krip Vorlund, a Free Trader, was a wanderer. All of the traders were rooted only to their ships; they had no ties to any world except as places to visit and exchange goods, and their only ambition was to be able to own their own space ships. But when Krip's crew came to the medieval planet Yiktor his soul became a wanderer into different bodies. It's all because he became a pawn in a plan by off-worlders to gain control of Yiktor as a base to achieve galactic control, and to do so they had to be able to conquer the Thassas, a small group of people of Yiktor with magic powers. Maelen, a Thassa trainer of a beast show and a Moon Singer saves Krip's life, but only by exchanging his body with that of a wolfish animal, later with a Thassa man. Together, Maelen and Krip become involved in the struggle to escape from the feudal battles, to attain safety for Yiktor, and to retrieve Krip's lost body. It's a compelling pilgrimage, well worth taking for fantasy/SF fans.