A boy's quest through the fabled star country of the zodiac is the theme of this richly inventive fantasy by a master-storyteller. The boy is Ludo, child of Bavarian mountain farmers, and his love for the aging family workhorse, Renti, is the motive for the dangerous journey that they undertake together.

The tale begins one winter's night when Renti breaks out from the stable and Ludo follows to bring him back. Instead, a falling star points the way to the star country, which the two enter through the House of the Archer, which a being half man, half horse presides over. From him, Renti learns that he must travel completely around the zodiac in order to claim his destiny as a star horse. Ludo, wishing to ease his way, decides to accompany him.

On their mission, Ludo and Renti meet the lords of all twelve houses, and each encounter provides another dramatic test of character. The evocation of this legendary world and the people who inhabit it shows Mary Stewart at her best.