The book takes place in the near future, when interplanetary flights have become commonplace for earthlings. The spaceship on which Alyosha and his friends were flying makes an emergency landing on one of the planets in the Orion constellation. When the ship's crew finds itself in a difficult situation, friends are sent to help. In this expedition full of dangerous adventures, our heroes had to learn the treachery of the inhabitants of the Green Planet, encounter unprecedented animals and unusual natural phenomena.