In The Castle Murders Louis Pean travels to Quebec with his two golden retrievers, Damon and Pythias, to research a novel on the French and Indian War. He visits an ancient castle on an island in the middle of the St.Lawrence River, accessible only by small plane in the late fall and winter months, and becomes involved in a murder mystery with links to the Mad King Ludwig of Bavaria, the poet T.S. Eliot, and a famous American university.