'King Coal' is a novel by Upton Sinclair that critiques the labor conditions in the coal mining industry, drawing attention to the exploitation of workers and the harsh realities of their lives. Sinclair, known for his investigative and social advocacy writing, aimed to shed light on social injustices and encourage reform through this and other works. For a detailed exploration of the book's themes, author insights, and its historical context, I recommend checking out a comprehensive literary database or the book's introduction in a recent edition.