The action takes place in the distant future on one of the habitable planets, the level of development of civilization which corresponds to the earthly Middle Ages. This civilization is observed by envoys from the Earth – employees of the Institute of Experimental History. Their activities on the planet are limited by the scope of the problem posed – Problems of Bloodless Impact. Meanwhile, in the city of Arkanar and the Arkanar Kingdom, terrible things happen: gray storm troopers catch and kill anyone who somehow stands out from the gray mass; an intelligent person, educated, finally, just a literate person can at any moment perish at the hands of eternally drunk, stupid and spiteful soldiers in gray robes. The court of King Arkanarsky, who was recently one of the most enlightened in the Empire, is now empty. The new minister of the protection of King Don Reba produced monstrous devastation in the world of Arkanar culture: who on espionage charges was imprisoned, called the Merry Tower, and then, after confessing all the atrocities, he was hanged in the square; who, broken morally, continues to live at court, writing poems that glorify the king. Some were rescued from certain death and transported beyond Arkanar by a scout from Earth Anton living in Arkanar under the name of the noble Don Rumata of Estor, serving in the royal guard.
In a small forest hut nicknamed by the people as the Drunken Berth, there are Rumata and Don Kondor, the General Judge and the Keeper of the big seals of the commercial republic of Soan and Alexander the Earthman, who is much older than Anton, besides he has lived on the planet for many years and is better oriented in the world the local situation. Anton agitatedly explains to Alexander Vasilievich that the situation in Arkanar goes beyond the basic theory developed by the Institute’s employees-a new, systematically acting factor arose; Anton does not have any constructive suggestions, but he is simply scared: here it is not a theory, Arkanar is typically a fascist practice, when animals kill people every minute. In addition, Rumata is concerned about the disappearance of Dr. Budaha after the crossing of the Irukan border, whom Rumata intended to transport outside the Empire; Rumata fears that the gray soldiers grabbed him. Don Kondor about the fate of Dr. Budaha is also unknown. As for the general situation in Arkanar, Don Condor advises Rumata to be patient and wait, not doing anything, to remember that they are just observers.
Returning home, Rumata finds waiting for his Kira – the girl he loves. Kira’s father is an assistant scribe in court, and his brother is a sergeant with stormtroopers. Kira is afraid to return home: the father brings paper from the Gay Tower for the correspondence, spattered with blood, and the brother comes home drunk, threatens to cut out all book readers to the twelfth tribe. Rumata announces to the servants that Cyrus will live in his house as a housekeeper.
Rumata is in the bedchamber of the king and, taking advantage of the ancient privilege of the Rumata clan – with his own hand to shoe the right leg of the crowned faces of the Empire, announces to the king that the highly... educated doctor Budach, whom he, Rumata, wrote out of Irukan specifically for the treatment of the sick gout of the king, was apparently captured by gray soldiers don Reba. To Rumata’s amazement, Don Reba is clearly pleased with his words and promises to present Budaha to the king today. At dinner, a hunched elderly man, whom Rumata had never been taken for granted, would never have been mistaken for Dr. Budach, known to him only from his writings, suggests that the king drink a medicine immediately prepared for them. The king drinks the medicine, having ordered Budacha himself to drink first from the cup.
This night in the city is restless, everyone seems to be waiting for something. Leaving Cyrus in the care of armed servants, Don Rumata goes on night duty to the bedchamber of the prince. In the middle of the night a half-dressed, gray-haired, frightened man bursts into the sentry room, in which Don Rumata recognizes the minister of the court, shouting: “Budakh poisoned the king! In the city rebellion! Save the prince!” But it’s too late – a man of fifteen storm troopers rushes into the room, Rumata tries to jump out the window, but, struck by the blow of a spear that has not penetrated the metal-plastic shirt, nevertheless, the stormtroopers manage to throw a net on him, they beat him with boots, drag him past the Prince’s door, Rumata sees heap of bloody sheets on the bed and loses consciousness.
After a while, Rumata comes to life, he is taken to the rooms of Don Reba, and then Rumata learns that the person who poisoned the king is not Budach at all: the real Budakh is in the Gay Tower, and the false Budah, who tried the royal medicine, in front of Rumata dies with a cry: “They cheated, it was poison, for what?” Then Rumata understands why Reba was so delighted with his words this morning: it was impossible to think of a better reason for the King of the false Budah, and from the hands of his first minister, the king would never have taken any food. Don Reba, who committed a coup, informs Rumata that he is the bishop and magister of the Holy Order, who came to power this night. Reba tries to find out from Rumata, for which he has been watching tirelessly for several years, who he is – the son of the devil or God or a man from a powerful overseas country. But Rumata insists that he is “a simple noble dong.” Don Reba does not believe him and admits himself that he is afraid of him.
Returning home, Rumata reassures the frightened by night events of Cyrus and promises to take her away from here far, far away. Suddenly there is a knock at the door – it was storm troopers. Rumata grabs the sword, but comes to the window of Cyrus, mortally wounded by arrows, released from the crossbow.
Distraught Rumata, realizing that the stormtroopers appeared on the orders of Reba, with his sword paving his way to the palace, neglecting the theory of “bloodless impact.” The patrol airship dumps checkers on the city with soporific gas, fellow intelligence officers select Rumata-Anton and send them to Earth.