At the end of the twentieth century in the human time system, the great antennae of the Earth began to search the sky for coherent signals, to determine if perhaps some other intelligence might be sending us a radio message. For over a hundred years the search continued, intensifying during the halcyon days of international science in the early twenty-first century, and then diminishing later, in the final decades of the century, after the fourth separate set of systematic listening techniques still failed to locate any alien signals.

In 2130, an unusual cylindrical object was observed approaching our solar system from the reaches of interstellar space. By that time, most thoughtful humans had concluded mat life was scarce in the universe and that intelligence, if it existed anywhere except on Earth, was exceedingly rare. How else, the scientists contended, can we possibly explain the lack of positive results from all our careful extraterrestrial search efforts of the last century?

The Earth was therefore stunned when, upon closer inspection, the object entering our solar system in 2130 was identified unambiguously as an artifact of alien origin. Here was undeniable proof that advanced intelligence existed, or at least had existed at some prior epoch, in another part of the universe. When an ongoing space mission was diverted to rendezvous with the drab cylindrical behemoth, which turned out to have dimensions greater than the largest cities on Earth, the investigating cosmonauts found mystery after mystery. But they were unable to answer the most fundamental questions about the enigmatic alien spacecraft. The intruder from the stars provided no definitive clues about its origin or purpose.