"It is a curious coincidence that no poet, or shall we call him investigator, has ever lived to conclude this particular story. His work has always been finished by another."
So says Doctor Carfax in Castle Dor. The words have an eerie quality when we learn that Sir Arthur Quiller-Couch died before completing his book which was later finished by Daphne du Maurier. The legend of Tristan and Iseult is one that has haunted poets and novelists alike with more than one version still extant. Castle Dor deals with the same legend set in 19th century Cornwall.
Tristan, a young knight and nephew to King Mark, brings home the Irish Princess Iseult who is to marry his uncle. The young couple accidentally (or intentionally in some versions) ingest a love potion meant for King Mark and Princess Iseult. They fall madly in love and pursue an adulterous relationship, hiding and scheming behind the King's back. They are betrayed by Iseult's maid and the King, intent on revenge, kills young Tristan with a poisonous arrow. In some versions he forgives the couple as long as Tristan agrees to leave. In this version, Tristan marries Iseult of the White Hands(namesake of Princess Isuelt), sister to Sir Kahedin, and leaves returning the Princess to her King.