Mid twenty-second century. The earthlings, who set out on the interstellar transport Ark to colonize the planets of the Bernard system, learned upon arrival that the place was occupied. On one of the planets, Tiadarkeral, its own intelligent life developed and an aggressive state of the natives, Tiadars, arose, led by the elite caste of the Highest. The level of technical development of the aborigines approximately corresponded to that on earth, and the order on the planet was reminiscent of the darkest times of the Middle Ages. Having discovered the arrival of earthlings, the aborigines tried to destroy the interstellar transport; in one of the skirmishes, several people died. Young cosmonaut Ivan Kapitanov, together with his friend Alexei Mashera, on instructions from the Ark Council, set off on a risky expedition to the native planet of the aborigines in order to conclude an alliance between earthlings and the clan of tiadars-Mercenaries. After long and dangerous adventures they succeeded. The Highest learned about the arrival of the ark embassy on the planet and, in order to prevent the emerging alliance, sent the guard to destroy the rebellious clan along with a delegation of people. Alexei died in the ensuing battle, and Ivan was seriously wounded. In response to this and to an attempt to attack the Ark with missiles with nuclear warheads, the earthlings destroyed the state of the Supreme Ones with a massive orbital bombardment. Power on the planet passed to the Mercenary clan. Their elders gave people the planet Ares, which is similar in natural conditions to Mars, for colonization, and allowed mining in the asteroid belt. Earthlings settled on Ares in several villages covered with hermetically sealed domes. On the second planet of the system, which has life - Aphrodite, there are remnants of the rule of the Highest - a little more than a thousand tiadars, loyal to the former elite. Ten years of peaceful life and terraforming of the planet inherited by people have passed, the undead remnants of the former enemies decide to take revenge on earthlings.