This book tells how the Templar makes the acquaintance of his arch-villain, destroys a dangerous death ray, and thereby saves the world from catastrophe and a second Great War.
Leslie Charteris (1907–1993), born Leslie Charles Bowyer-Yin, was a half-Chinese, half English author of primarily mystery fiction, as well as a screenwriter. He was best known for his many books chronicling the adventures of Simon Templar, alias "The Saint."
Several short stories featuring Templar are either science fiction or fantasy (typically dealing with odd inventions or monsters).
Leslie Charteris. Wikipedia.