The book is set following the abortive Martian attack depicted in "Fighters from Mars", much more devastating and global than in H. G. Wells' "The War of the Worlds", though in both works the onslaught is thwarted when the aliens die from bacterial illness. Determining that the Martians will inevitably return, Earth's leaders, including U.S. President William McKinley, Queen Victoria, Kaiser Wilhelm II, and Emperor Mutsuhito, unite the world against the common threat and plan an attack on Mars. American inventor Thomas Edison leads a group of scientists studying derelict Martian equipment; they are able to develop an anti-gravity device powered by electric repulsion as well as a disintegration ray.