Having read Royal Flash, I also read its inspiration, The Prisoner of Zenda, Anthony Hope’s classic adventure novel. Rudolf Rassendyll, a young British aristocrat, decides to visit Ruritania, where his distant cousin and doppelgänger, the dissipated Rudolf Elphberg, is about to be crowned king. The future king has a half brother, “Black” Michael, who begrudges him the throne and also covets his fiancée, Princess Flavia. Michael kidnaps the king and the king’s friends, in a desperate attempt to preserve political peace, persuade Rassendyll to impersonate the king. The imposture is successful and a stalemate is achieved: Michael cannot reveal that he holds the real king prisoner at his castle in Zenda, while Rassendyll dare not reveal that he is not the true king. Rassendyll and Flavia fall in love with each other—she thinks he is a changed man. Eventually Rassendyll must rescue his cousin from Zenda before it is too late.
The story is exciting enough, but the writing is jejune and would not pass muster today. Royal Flash is a better book.