Set during World War I, "The Secret Service Submarine" centers on the daring and clandestine operations of a submarine crew engaged in espionage and warfare. The novel likely follows the crew's missions, which involve covert activities, encounters with enemy forces, and high-stakes naval battles. The story captures the tension and drama of submarine warfare, a relatively new and highly dangerous aspect of naval combat at the time.Thorne's writing is characterized by its fast-paced narrative, vivid descriptions, and a focus on heroism and adventure. The novel would have appealed to readers interested in war stories and the technological innovations that were emerging during World War I, especially the strategic use of submarines.