The novel tells the prophetic story of mans harnessing of the newly-discovered power of the atom, how this power nearly destroys civilization in a catastrophic war and foreshadows nuclear warfare years before research began and describes the chain reactions involved and the resulting radiation. It is presented as a history of the important events of the 20th century, jumping back and forth amongst narratives of different eyewitnesses and major players in those events.
The World Set Free is a remarkable example of how science and science fiction can interact with and build upon each other. Wells describes a weapon of enormous destructive power, used from the air that would wipe out everything for miles, and actually used the term atomic bombs.
