Astronauts are urgently sent from the planet Korzun to another planet. During the journey, the ship is supposed to be destroyed, but the verdict is canceled. On a cargo ship under external control—carrying something strange—astronauts are sent to the planet ZET. Puéila tells about a similar strange cargo that had accompanied an astronaut—Izveyla—to planet X, where a biological explosion occurred, destroying everything created by humans and nearly wiping out all living things. On the planet Ts epran, the ship picks up a group of exhausted, worn-out people. The commander tries to find out what happened on the planet, but the people keep silent. The attempt by the astronauts to go out into the world and report the catastrophe fails. The ship goes on. Sequel—on the planet ZET.