Vsadniki niotkuda. Rai bez pamiati. Serebrianyi variant - Aleksandr Abramov, Sergei Abramov

"Riders from nowhere." Soviet polar explorers working in Antarctica, first stumble upon an atypical ice sheet, and then meet with their twins, disappearing after a while. Soon they discover the fallen American plane. Its pilot says he was attacked by pink "clouds" - gaseous reddish-hued objects that move quickly regardless of the wind. To resist these aliens, or as they were called, "riders from nowhere," all humanity unites.
"Paradise without memory." Heroes of "Riders from Nowhere", Soviet polar explorer Yuri Anokhin and American pilot Donald Martin, find themselves in a strange place where people do not have the experience of modern humanity. Remembering how the pink "clouds" created copies of people and objects, Anokhin and Martin guess that where they got is not the Earth. But they find friends here and help them, including to gain skills that their creators did not give.
"Silver version." Anokhin and Martin again find themselves on the "cloned Earth" and meet with their old friends from "Paradise without memory", however, here has passed fifty years. Their friends are now elderly and significant people, but they still need the help of earthlings.
The trilogy of Alexander and Sergei Abramov is the highest level of fiction, which combines scientific authenticity, brightness of images, and the fascination of the plot.