These three volumes form the  “Satan and Iscariot” trilogy. Actually, Karl May only called the third volume by that name whilst others called it “The Swindler of the Millions”.
The story that began in the mountains of the Northern Mexico territory, where the first of the three notorious Melton character appears in “The Rock Castle” continues in “Kruger Bei” with yet more murderous betrayals through the deserts of northern Africa. Finally it concludes in the final book, “Satan and Iscariot”, with a fast moving tale that returns to the southern territories of the Unites States, Louisiana, New Mexico and Arizona, a tale that relates the pursuit of these “Swindler of the Millions”, until the final judgment is rendered to the purveyors of lawlessness and murder.