The action takes place in the distant future on one of the inhabited planets, the level of development of civilization which corresponds to the earthly Middle Ages. This civilization is being watched by envoys from Earth - employees of the Institute of Experimental History. Their activity on the planet is limited by the scope of the problem posed - the Problems of Bloodless Impact. In the meantime, terrible things are happening in the city of Arkanar and the Arkanar kingdom: gray stormtroopers catch and kill anyone who stands out from the gray mass anyway; an intelligent man, educated, finally, just literate can die at any time at the hands of forever drunk, stupid and evil soldiers in gray robes. The courtyard of the King of Arkanar, recently only one of the most enlightened in the Empire, is now empty. The new Minister for the Protection of King Don Reba (recently emerged from the office of the ministry an inconspicuous official, now the most influential person in the kingdom) carried out monstrous devastations in the world of Arkanar culture: who was charged with espionage in a prison called the Fun Tower, and then, confessing to everyone atrocities hanged in the square; who, morally broken, continue to live at court, peeing verses glorifying the king. Some were saved from certain death and transported outside Arkanar by a scout from the Earth Anton, who lives in Arkanar under the name of the noble don Rumata Estorsky, who is serving in the royal guard.

In a small forest hut, nicknamed the Drunken Den by the people, there are Rumata and Don Condor, the General Judge and the Keeper of the large seals of the trade republic Soan and the earthling Alexander Vasilievich, who is much older than Anton, in addition, he has lived on the planet for many years and is better oriented in the local setting. Anton excitedly explains to Alexander Vasilyevich that the situation in Arkanar goes beyond the framework of the basic theory developed by the Institute’s employees — a new, systematically acting factor has arisen; Anton has no constructive suggestions, but he’s just scared: here it’s not about theory, in Arkanar it’s typical fascist practice, when animals kill people every minute. In addition, Rumata is concerned about the disappearance after crossing the Irukan border of Dr. Budah, whom Rumata was going to smuggle outside the Empire; Rumata fears that he was captured by gray soldiers. Don Condor does not know anything about the fate of Dr. Budah. As for the general state of affairs in Arkanar, don Condor advises Rumate to be patient and wait, doing nothing, to remember that they are just observers.

Returning home, Rumata finds Kira waiting for him - the girl he loves. Kira's father is an assistant to the scribe in court, and his brother is a sergeant of the stormtroopers. Kira is afraid to return home: her father brings papers splattered with blood from the Fun Tower for correspondence, and his brother comes home drunk, threatens to cut all the books out to the twelfth knee. Rumata announces to the servants that Kira will live in his house as a housekeeper.

Rumata appears in the bed of the king and, taking advantage of the most ancient privilege of the Rumat family to personally shoe the right foot of the crowned persons of the Empire, announces to the king that the highly trained doctor Budakh, whom he, Rumata, was discharged from Irukan specifically to treat a patient with gout of the king, was obviously captured by gray soldiers Don Reba. To the amazement of Rumata, Don Reba is clearly pleased with his words and promises to introduce Budah to the king today. At dinner, a hunched elderly man whom the puzzled Rumata would never have taken for Dr. Budaha, known only to him from his writings, invites the king to drink the medicine he immediately prepared. The king drinks the medicine by ordering Budah to first take a drink from the goblet himself.

This night in the city is restless, as if everyone was waiting for something. Leaving Kira in the care of armed servants, Don Rumata goes on night duty to the prince's bedchamber. In the middle of the night, a half-dressed, terrified blue man bursts into the guardhouse, in which don Rumata recognizes the Minister of the Court, shouting: “Budakh poisoned the king! There is a riot in the city! Save the prince! ” But it’s too late - about fifteen stormtroopers burst into the room, Rumata tries to jump out the window, however, struck by the blow of a spear, which has not yet broken through the metal-plastic shirt, he falls, the stormtroopers manage to throw a net on him, they beat him with boots, drag him past the prince’s door, Rumata sees a heap of bloodied sheets on the bed and faints.

After some time, Rumata comes to his senses, he is taken to Don Reba’s chambers, and here Rumata learns that the person who poisoned the king is not Budakh at all: the real Budakh is in the Fun Tower, and the false Budakh, who tried the royal medicine, in front of Rumata dying with a cry: "Deceived! It was poison! For what?" Here, Rumata understands why in the morning Rab was so happy about his words: it was impossible to palm off the king of false Budakh and it was impossible to come up with a king, and from the hands of his first minister the king would never have taken any food. Don Reba, who committed the coup, informs Rumate that he is the bishop and master of the Holy Order, who came to power this night. He is trying to find out from Rumata, whom he has been tirelessly watching 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 don.” Don Rab does not believe him and admits himself that he is afraid of him.

Upon returning home, Rumata reassures Kira, frightened by the nightly events, and promises to take her far, far away from here. Suddenly there is a knock on the door - it was the attack aircraft. Rumata grabs her sword, but Kira, who approaches the window, falls, mortally wounded by arrows fired from a crossbow.

Distraught Rumata, realizing that the stormtroopers appeared on the orders of Reba, paves his way to the palace with his sword, neglecting the theory of "bloodless influence." A patrol airship throws drafts of soporific gas onto the city, fellow intelligence officers pick up Rumata-Anton and send them to Earth.