Rupert of Hentzau by Anthony Hope

The story is set within a framing narrative told by a supporting character from The Prisoner of Zenda. The frame implies that the events related in both books took place in the late 1870s and early 1880s. This story commences three years after the conclusion of Zenda, and deals with the same fictional country somewhere in Germanic Middle Europe, the kingdom of Ruritania. Most of the same characters recur: Rudolf Elphberg, the dissolute absolute monarch of Ruritania; Rudolf Rassendyll, the English gentleman who had acted as his political decoy, being his distant cousin and look alike; Flavia, the princess, now queen; Rupert of Hentzau, the dashing well-born villain; Fritz von Tarlenheim, the loyal courtier