The Earth has become the embodiment of a humanistic utopia. The head of the Commission on Contacts with Extraterrestrial Civilizations, Rudolf Sikorski, instructs Maxim Kammerer to find Lev Abalkin, a progressor who mysteriously disappeared after contact with the supercivilization of the Wanderers. Abalkin's group explored the planet Nadezhda, which was destroyed by a monstrous experiment conducted there by the Wanderers. After contacting them, Abalkin kills his partner and flies to Earth to start a process similar to the one that destroyed Nadezhda. Kammerer manages to track down Abalkin, but Abalkin is always one step ahead of him.
