It is spring in Baker Street, and London is preparing itself for the wedding of the year. It will be an international spectacle in which the young and popular Count Rudolph Absberg, a political exile from his native land, will take the hand of the beautiful and accomplished Princess Sophia Kubinova. A lot depends on the marriage, for it is hoped that the union will ensure the security and independence of their homeland. When the princess subsequently disappears in dramatic circumstances, members of the British establishment are quick to call on Mr Sherlock Holmes. He, in turn, needs the gifts of long-standing housekeeper Mrs Hudson and her able assistant, housemaid Flotsam, to solve this puzzling case on which rests the fate of nations.