In the 16th century, the wicked Archduke Axel, the "Leopard of Tryce," plots revenge on Chase Longshanks. In a long cross-country race ridden by the two men, Chase had won Axel's estate, plus all of its huge debts. Now, in 1930, Crispin Agincroft (hero of "Crispin and the Great Tree"), discovers the Leopard's plan to attack and destroy Longshanks Hall. Crispin, able to move backwards and forwards through time by using his enchanted umbrella, launches an effort to assist Chase and foil the Leopard's design. The story builds to a spectacular double climax and a cryptic conclusion.