Men had built cities before, but never such a city as Diaspar; for millennia its protective dome shutout the creeping decay and danger of the world outside. Once, it held powers that rules the stars. But then, as legend had it, The invaders came, driving humanity into this last refuge. It takes one man, A Unique to break through Diaspar's stifling inertia, to smash the legend and discover the true nature of the Invaders.

On the moon an enigma is uncovered. So great are the implications of the discovery that, for the first time, men are sent out deep into the solar system. But before they can reach their destination, things begin to go wrong. Horribly wrong.

To the spaceship Discovery, floating in the silent depths of space since Dave Bowman passed through the alien 'Star Gate', comes Heywood Floyd on a mission of recovery. What he finds near Jupiter is beyond the imaginings of any mere human.