Set primarily in Milan, Italy, it features Leonardo da Vinci, his servant Salai, and duchess Beatrice d'Este.

The book was published by Atheneum in 1975, manufactured by Halliday Lithograph Corporation with ten black-and-white museum plates of da Vinci paintings and drawings, of which several figure in the story.

The son of a poor shoemaker, Salai is a cutpurse caught in the act by the master, whose grasp and visage he mistakes for the hand and face of God.

"She's small and dark and perfectly plain", Salai says when he first sees Beatrice; when they meet by accident, she is "trying to get the sun to make me blond and beautiful".

Isabella visits and envies her sister for "the intellectuals, the gifted, the skilled craftsmen; the very elements who were drawn naturally to Beatrice.

She does confide disappointment in the massive Leonardo's horse, conveys insight regarding the master's talent, and admonishes Salai to take some responsibility for that.