Romantic stories about the royalty of a fictional kingdom were common, for instance Robert Louis Stevenson's "Prince Otto" (1885). But it was the great popularity of Anthony Hope's "The Prisoner of Zenda" (1894) which set the type, with its handsome political decoy restoring the rightful king to the throne, and resulted in a burst of similar popular fiction, such as George Barr McCutcheon's Graustark novels (1901–27) and Frances Hodgson Burnett's "The Lost Prince" (1915), Edgar Rice Burrough's "The Mad King" of Lutha (1914), and other homages. In children's literature, the 1938–39 The Adventures of Tintin comic "King Ottokar's Sceptre" eschewed literal romance, but is an adventure about foiling a plot to depose the king of Syldavia. Literary critic John Sutherland says Eric Ambler brought the Ruritarian romance to "its highest pitch" with his 1939 novel "The Mask of Dimitrios". An earlier venture into Ruritanian themes was Ambler's very first novel, "The Dark Frontier" (1936), set in the fictional Balkan country of Ixania.