They mustn't harm a human being, they must obey human orders, and they must protect their own existence...but only so long as that doesn't violate rules one and two. With these Three Laws of Robotics, humanity embarked on a bold new era of evolution that would open up enormous possibilities, and unforeseen risks.

His name was Biron Farrill and he was a student at the University of Earth. A native of one of the helpless Nebular Kingdoms, he saw his home world conquered and controlled by the planet Tyrann - a ruthless, barbaric Empire that was building a dynasty of cruelty and domination among the stars. Farrill’s own father had been executed for trying to resist the Tyrann dictatorship and now someone was trying to kill Biron. But why? His only hope for survival lay in fleeing Earth and joining the rebellion that was rumored to be forming somewhere in the Kingdoms.

It is the year 12,020 GE and Emperor Cleon I sits uneasily on the Imperial throne of Trantor. Here in the great multidomed capital of the Galactic Empire, 40 billion people have created a civilization of unimaginable technological and cultural complexity. Yet Cleon knows there are those who would see him fall - those whom he would destroy if only he could read the future.

Only a few know the terrifying truth - an outcast Earth scientist, a rebellious alien inhabitant of a dying planet, a lunar-born human intuitionist who senses the imminent annihilation of the Sun... They know the truth - but who will listen? They have foreseen the cost of abundant energy - but who will believe?These few beings, human and alien, hold the key to the Earth's survival.

A collection of 20 classic short stories by Isaac Asimov, author of the Foundation series, featuring the definitive and only in-print version of “Nightfall”.