In 2061, when two Suns share the skies of Earth, Halley's Comet returns to the inner Solar System - and a 21st century trillionaire's space yacht actually lands on the comet. Among the famous crew is centenarian Heywood Floyd, survivor of two encounters with the mysterious monoliths which seem to control the destiny of both the human race and whatever strange creatures inhabit the mysterious, cloud-shrouded Jovian moon, Europa.