An experiment has gone terribly wrong. Dr. Peter Hobson has created three electronic simulations of his own personality. One will test life after death; another, immortality. The third one is the control unit. But now all three have escaped from Hobson's computer into the worldwide electronic matrix. And one of them is a killer.

When prospector Bob Broadhead went out to Gateway on the Heechee spacecraft, he decided he would know which was the right mission to make him his fortune. Three missions later, now famous and permanently rich, Robinette Broadhead has to face what happened to him and what he is...in a journey into himself as perilous and even more horrifying than the nightmare trip through the interstellar void that he drove himself to take!

Roger Torraway watched in horror as the monster lurched, toppled over and died. Project Man Plus had gone suddenly and drastically wrong. The race to colonize Mars was too important, too costly, and America was already too committed, for plans to be scrapped. They would have to make a new Martian. And Roger Torraway was it, candidate for the endless surgery, operation after painful operation, that would enable him to survive on that faraway planet.

The Overlords appeared suddenly over every city - intellectually, technologically, and militarily superior to humankind. Benevolent, they made few demands: unify earth, eliminate poverty, and end war. With little rebellion, humankind agreed, and a golden age began.

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.