The book features Thomas Edison as the primary character, though neither Edison nor H. G. Wells were involved in its creation (although the 2010 edition published by Apogee Books of Canada includes the credit "written in collaboration with Edison"). Set after the devastating Martian attack in the previous story, the novel depicts Edison leading a group of scientists to develop ships and weapons, including a disintegration ray, for the defence of Earth. Edison and company fight the aliens in space and on Mars, eventually causing a flood that defeats the enemy and forces an end to hostilities. Serviss wrote himself into the story as a professor whom Edison consults; also appearing are scientists such as Edward Emerson Barnard, Lord Kelvin, Wilhelm Röntgen, and Silvanus P. Thompson, and heads of state such as Queen Victoria, U.S. President William McKinley, Kaiser Wilhelm II, and Emperor Mutsuhito.