The Other End of Time — Frederik Pohl

Earth, 2031: Alien contact.

Signals are received: a crude depiction of creatures pantomiming the cataclysmic destruction of the universe.

Soon after, scientists note unusual radiation emanating from an abandoned Earth-orbital observatory. When a group of scientists and astronauts board the observatory to investigate, they are taken prisoner. An unsuspecting Earth has just become part of a vast interstellar war.

For the human prisoners, this minor skirmish in a vast war becomes a fantastic adventure. The hunters become the hunted, the prey the predators, and nothing is as it seems. The only sure thing is that the winners will rule eternity at...The Other End of Time.