Desc: The King of the Beggars: Vigo Grexville, a foreign spy, king of the city's beggars, breaks into General DuRoy's house to secure possession of important government papers. DuRoy's daughter, Mona, interrupts the criminal, who, however, carries her off before she can give the alarm. As Mona has seen his face, Grexville decides to keep her a lifelong prisoner in his castle. From the papers the criminal learns that Mona is heiress to her father's vast fortune and he determines upon a bold coup. He forces Mona to write a letter to the general, telling him that for reasons of her own she stole the government papers. On receipt of the letter DuRoy is heartbroken, but Mona's fiancé, Dr. Garth, refuses to believe his sweetheart's guilt, and declares he will unravel the mystery. A night or two later Grexville visits the general's home and shoots him, leaving behind a revolver to give the tragedy the appearance of suicide. He then tells Mona that unless she agrees to marry him and share her father's fortune with him she will never see the outside world again. Mona is obdurate and by means of a swallow which has built its nest outside her prison window, she sends a message earnestly entreating the finder to communicate with Dr. Garth. Some days later Garth receives the letter, but it has been so badly mutilated that all he can learn is that Mona is a prisoner in the hands of a man who calls himself "King of Beggars." In order to solve the mystery Garth disguises himself and mixes with the beggars of the city. For a month his search is without avail, but at last he meets the king, whom he follows to his home. In a struggle with Grexville, Garth is overpowered and flung through a secret trapdoor into a sewer beneath the castle. He makes his way out by using an explosive cartridge he carries, and succeeds in rescuing Mona from her prison, which has caught fire. They then hasten to inform the police and a strong force is sent to arrest Grexville, who is attending a state ball. Grexville fights his way from the ballroom and escapes in a waiting motorcar, with the police in hot pursuit. Grexville's chauffeur is killed, and the crook badly wounded meets his doom when the motorcar plunges over a steep cliff. Later Mona finds happiness as the bride of her faithful lover.