The novel follows the Dreadnought Boys a group of adventurous and resourceful young protagonists as they embark on a thrilling journey involving a submarine. The story is set during World War I and centers around the boys' experiences with the submarine including their encounters with naval operations espionage and various challenges at sea. As the boys navigate their underwater adventure they face dangers and mysteries showcasing their bravery ingenuity and teamwork. The narrative combines elements of military adventure with the excitement of submarine warfare reflecting the era's fascination with naval technology and heroism.