This is the twenty-fifth century according to earthly reckoning. The planet Stika, which was already described in the book “Pilot’s Star,” lives a peaceful life, but disturbing news comes from all sides. On interplanetary flights, attacks by robber-raiders on spaceships have become more frequent. Stika is under threat of attack, an army of mercenaries is striving for power on the planet Kautilya, and a revolution begins on the inhabited star Astrion. And all inhabited worlds, including Earth, are under the threat of an unprecedented energy crisis caused by nebulae - a new, unexplored and dangerous phenomenon in outer space. The heroes of the book - a military pilot from Stika, an ethnographer from Earth and a girl from Kautilya - by coincidence find themselves at the center of these events. Will they be able to unravel the mysteries of the new phenomenon? Will the inhabitants of the inhabited worlds be able to defend their freedom?