A mysterious black sphere is discovered in the orbit of Mars. The Achilles is sent to investigate. After the bedraggled six-person crew wake from eight months hibernation, the Sphere is transmitting a single word in every Earth language...

Brilliant young general Macbeth pulls off a glorious victory in battle before returning to an indolent court where honours are dispensed by whim. Spurred on by prophesying drifters and an ambitious wife, Macbeth sets his sights on the throne...