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.

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.

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.

At first, only a few things are known about the celestial object that astronomers dub Rama. It is huge, weighing more than ten trillion tons. And it is hurtling through the solar system at inconceivable speed. Then a space probe confirms the unthinkable: Rama is no natural object. It is, incredibly, an interstellar spacecraft. Space explorers and planet-bound scientists alike prepare for mankind's first encounter with alien intelligence.

In the 23rd century, pioneers have escaped the crowded earth for life in self-sustaining orbital colonies. One of the colonies, Rotor, has broken away from the solar system to create its own renegade utopia around an unknown red star two light-years from Earth: a star named Nemesis. Now a 15-year-old Rotorian girl has learned of the dire threat that nemesis poses to Earth’s people - but she is prevented from warning them. Soon, she will realize that Nemesis endangers Rotor as well.