The Drums of Jeopardy is a 1920 American novel by Harold MacGrath. The story was serialized by the The Saturday Evening Post beginning in January of 1920.
In 1922 the book was made into a Broadway play and the following year a motion picture. A second film version appeared in 1931.
It is said that a young Boris Karloff, who previously had a few uncredited film roles, chose his stage name for his first screen credit in 1920 from a Russian mad scientist character named "Boris Karlov" in this novel. The name "Boris Karlov" was used from MacGrath's book for the 1922 Broadway play, but by 1923 with actor Boris Karloff using the similar sounding variation, the film version renamed the character, played by Wallace Beery, "Gregor Karlov." In the 1931 film version, however, with Warner Oland playing the character, the mad scientist's name is restored to "Boris Karlov," less than a year before Frankenstein would make Boris Karloff a household word for generations. Ironically, Boris Karloff would play many mad scientists on screen, but never "Boris Karlov." (Wikipedia)