The Amar discovered Earth in 2644 BC, arrogantly taking specimens, human and animal, back to their home world. They also took their doom?measles?which claimed 89 percent of their population. Cities died; continents died. A single planetary culture arises as the Amar recreate their society. The humans, the sole occupants of a dead continent, survive, reproduce, and create their own society. When discovered, the humans are too numerous to repatriate to Earth. The Amar adopt them into their society. When the Amar can again space-travel, the humans are denied repatriation as, now technologically advanced, they would disrupt the independent development of Earth. Also the Amar are ashamed of their earlier abductions. Yet the humans desire a home of their own. In 1882 the Amar return to Earth, only to establish a clandestine observation facility on the moon. Radio in the early 1900s and later television allow the Amar to remotely study Earth. Observing the damage being done to Earth?s ecology, scientist Kargon, shocked by the rate of decay, devised a plan of his own to save Earth. Co-opting Amar?s humans, he promises to unleash viral destruction on Earth. With Earth?s population decimated and the planet?s ecology saved, the humans of Amar could return. Kargon and a coconspirator escape, only to crash in outback Australia. Here they are still able to concoct a scenario that will bring about their goal. An Amar recovery team sent to apprehend the renegades meets problems of their own. Aided by Chris and Mark, they arrange their rescue. The encounter terrifies Chris, though Mark burns to visit Amar, using his aid as a bargaining chip to be invited. Mark departs for Amar. Once there, he must negotiate the political machinations and cultural differences while unraveling Kargon?s plan. Eventually, Mark returns to Earth to discover that Kargon has betrayed his supporters and his virus has been unleashed