Spacious cozy kitchen. There is nobody, only the Cat is warming at the burning hearth. A casual passerby, tired of the road, enters the house. He calls one of the hosts, but there is no answer. Then he turns to Kot and finds out that the owners - archivist Charlemagne and his daughter Elsa - left the yard, and he, Kot, is trying to rest his soul, because the family is in great sorrow. After the insistent requests of Lancelot, the Cat says: a disgusting Dragon settled over their city four hundred years ago, who chooses a girl every year, takes her to his cave, and no one sees her again (according to rumors, all the victims die from disgust there). And now it’s Elsa’s turn. The returning owners are very welcoming with an unexpected guest. Both are calm, Elsa invites everyone to dinner. Lancelot is struck by their composure, but it turns out they just resigned themselves to their fate. Two hundred years ago, some fought the Dragon, but he killed all the brave souls. Tomorrow, as soon as the monster takes Elsa away, her father will also die. Lancelot's attempts to awaken the will to resist in Charlemagne and his daughter are futile. Then he announces that he is ready to kill the Dragon.
There is an increasing noise, whistle and howl. “Easy on sight!” - says the cat. An old man enters. Lancelot looks at the door, waiting for the monster to come in. And this is it - Charlemagne explains that sometimes the Dragon takes the form of a person. After a short conversation, Lancelot calls him to battle. The dragon turns red and promises the daring immediate death.
The archivist intervenes - he recalls that 382 years ago, the Dragon signed a document according to which the day of the battle is not appointed by him, but by his rival. The dragon replies that he was then a sentimental boy, and now he is not going to pay attention to that document. The cat jumps out the window, promising to tell everyone everything. The dragon is indignant, but in the end agrees to fight tomorrow and leaves.
Elsa assures Lancelot that in vain he started everything: she is not afraid to die. But Lancelot is adamant - you need to kill the villain. At this time, the Cat runs in with the message that it notified the familiar cats and all of their kittens, who immediately spread the news of the upcoming fight throughout the city. The Mayor appears. He attacks Lancelot with reproaches and convinces him to leave as soon as possible. The next son of the Burgomaster, Henry (the former groom of Elsa, and now the lackey and personal secretary of the Dragon), demands that he be left alone with the girl. He gives her the owner’s order to kill Lancelot and hands him a poisoned knife. Elsa takes the knife, deciding that she will kill herself.
Having met in the city square, the Mayor and his son discuss upcoming events. Henry reports that his overlord is very nervous. He asks his father if he doubts the victory of the Dragon. The burgomaster realizes that this is a secret interrogation on behalf of the owner. In turn, he tries to find out from Heinrich if the Dragon ordered "to quietly poke Mr. Lancelot", and, having not received a direct answer, stops the conversation.
On the square with fake solemnity, a ceremony of presenting weapons to the enemy of the Dragon takes place. In fact, he is offered a copper basin from the barber instead of a shield, they are handed a certificate that the spear is under repair, and they report that they did not find knightly armor in the warehouse. But the Cat, who settled on the fortress wall, whispers to Lancelot the good news. His words were interrupted by howling and whistling, after which the Dragon appears. He orders Elsa to say goodbye to Lancelot, and then to kill him. She obeys. But - this is no longer a farewell, but an explanation of the two lovers, and it ends with a kiss, and then Elsa throws a knife hanging on her belt in the well and no longer wants to listen to the Dragon. You have to fight, Dragon understands. And leaves.
The cat draws Lancelot's attention to several drovers with a donkey. They give Lancelot a carpet-plane and an invisible hat, as well as a sword and spear. Having put on a hat, Lancelot disappears.
The palace doors swing open. Three giant heads, huge paws and burning eyes of the Dragon are visible in smoke and flame. He is looking for Lancelot, but that is nowhere to be found. Suddenly, the sound of a sword is heard. One by one, the Dragon's heads fall to the square, calling for help, but no one, not even the Burgomaster and Henry, pays attention to them. When everyone leaves, appears, leaning on a bent sword, holding an invisible hat, Lancelot. He is seriously wounded and mentally says goodbye to Elsa: death is near.
After the death of the Dragon, the Burgomaster seizes power. Now he is called the president of the free city, and the place of the burgomaster went to his son. All objectionable are thrown into prison. Citizens, as before, in submission and humility. The new ruler, proclaiming himself the winner of the Dragon, is going to marry Elsa. But fear does not leave him that Lancelot will return. He sends his son to talk with Elsa and find out if she has any news of Lancelot. In a conversation with Elsa, Henry is full of feigned sympathy, and Elsa, who believes in his sincerity, tells him everything she knows. Lancelot will not return. The cat found him wounded, laid him on the back of a familiar donkey and led them out of the city into the mountains. On the road, the hero’s heart stopped beating. The cat told the donkey to turn back so that Elsa could say goodbye to the deceased and bury him. But the donkey became stubborn and moved on, and the Cat returned home.
The burgomaster is delighted: now he has no one to fear and you can play a wedding. Guests arrive, but the bride suddenly refuses to become the wife of the president of the free city. She speaks to those gathered, begging them to wake up: has the Dragon really not died, but this time embodied in a multitude of people, really, no one will intervene for her ?! At this time, Lancelot appears, who was cured by friends in the distant Black Mountains. The frightened Mayor tries to be nice to him, the guests are hiding under the table. Elsa does not immediately believe her eyes. Lancelot admits that she really missed her, she - that she loves him more than ever.
Henry and the Mayor try to escape, but Lancelot stops them. For a whole month he wandered around the city in an invisible hat and saw what a terrible life people live who have lost the ability to resist evil. And those who he liberated from the Dragon a year ago did this! The burgomaster and Henry are taken to prison. Lancelot is ready for hard work - to kill the dragon in disfigured souls. But this is ahead, and now he takes Elsa by the hand and tells the music to play - the wedding will still take place today!
