The crew of a space truck following the route Moon - Mercury picks up an alien in outer space, who turns out to be an extremely voracious monster... A group of terrestrial scouts gets stuck in one of the parallel worlds when a subspace tunnel collapses, and now they are faced with an almost impossible task - to survive and return home...Several dozen children who escaped from a starship that made an emergency landing become captives of a mysterious planet on which adults die for unknown reasons...The most incredible events take place in the works of the popular science fiction writer Alexander Gromov, winner of numerous literary awards.