Harold Bell Wright 
The mine with the iron door [EPUB ebook] 

Harold Bell Wright (1872 – 1944) was a best-selling American writer of fiction, essays, and nonfiction. He is said to have been the first American writer to sell a million copies of a novel and the first to make $1 million from writing fiction.
Between 1902 and 1942 Wright wrote 19 books, several stage plays, and many magazine articles. More than 15 movies were made or claimed to be made from Wright’s stories. (from wikipedia.org)