The action takes place in the XIII century. in France, in Languedoc and Brittany, where the Albigoyan rebellion flares up against which the pope will organize a crusade. The army, designed to help overlords, is moving from the north.
The play begins with a scene in the courtyard of the castle, where the watchman Bertrand, nicknamed the Knight of Misfortune, sings a song heard from a visiting juggler. The refrain of this song, which tells about the hopelessness of life, there is only one way out - to become a crusader, are the lines: “The law is immutable to the heart - Joy - One suffering!” It is they who will become “cross-cutting” for the whole play.
Alice, the court lady, asks Bertrand to stop singing: her mistress, seventeen-year-old Isora, in whose veins the Spanish blood flows, the wife of the castle owner, is unhealthy.
The chaplain pesters Alice with obscene offers. She rejects him indignantly, but she herself does not mind flirting with a page by Aliskan. He, however, rejects her.
The doctor diagnoses Isore with melancholy. She sings a song about Joy-Suffering, understanding suffering as "joy with the sweet." He plays chess with a page - and makes fun of him. He taunts an unknown songwriter. Izora leaves. Alice seduces Aliskan. Count Archimbaut, the owner of the castle, sends Bertrand (to whom he belongs without any respect) to scout: is the army far in a hurry to help? The chaplain, meanwhile, hints at the mistress's bad inclinations: she reads romance novels ... A doctor who arrives announces melancholy.
Izora asks Bertrand during his journey to find the songwriter. He agrees. The count sends his wife into captivity - in the Tower of the inconsolable Widow.
In Brittany, Bertrand met with the Truver Gaetan, the lord Traumenek: he almost killed him during the fight, but soon they reconciled and even had a friendly conversation in the house of Gaetan. It is he who turns out to be the author of the cherished song. On the ocean, Gaetan teaches Bertrand to listen to the voice of nature.
The good news brings Count Bertrand: he saw the troops. As a reward, he asks permission to sing at the festival to the juggler, whom he brought with him, and to release the count’s wife from the Tower, where, judging by the conversations in the kitchen, she is kept very strictly. Indeed: Isora yearns for imprisonment. Only dreams of a knight support her. Hopes are strengthened after the unfortunate woman takes on her account a love note addressed to Aliskan Alice, where a date is set for the moonrise. Meanwhile, Bertrand, in an interview with Gaetan, is trying to understand: “How can suffering become joy?” Izora, having waited inconsolably at the window, suddenly sees Gaetan - and, throwing him a black rose, loses consciousness from an overabundance of feelings. The count, thinking that imprisonment is the reason, announces the release. In the courtyard of the castle Bertrand prays for the health of the unfortunate.
In a flowering meadow at dawn, Aliskan is angry at Alice, who did not come on a date, and again surrenders to dreams of Isor. Having brought Gaetan the clothes of a juggler, Bertrand sees a black rose from him - and asks for it for himself. On the May Day, Aliskana is knighted. Minstrels compete in singing: a song about war is rejected by the count, a song about love for girls and their native land receives an award. Gaetan's turn comes. After his song about Joy-Suffering, Izora loses his senses. Gaetan disappears into the crowd. Waking up, Izora turns his attention to Aliskan. Meanwhile, the rebels are approaching the fortress. Bertrand fights best of all: the defenders of the fortress owe him his victory. But the count refuses to admit the obvious, although it frees the wounded Bertrand from the night guard. Meanwhile, the unfaithful Alice makes an appointment with the chaplain to meet in the courtyard at midnight, and Izora, languishing in the spring from a hearty void, asks the watchman to warn about the arrival of unwanted guests during her meeting with her lover. Aliskan unexpectedly acts as such. But their date is opened by Alice and the chaplain. The last is calling the count. At that moment, Bertrand, exhausted by his wounds, falls dead. With the sound of a sword, he frightens off Aliskan. The young lover runs - and the count bursting into his wife’s chambers does not find anyone.
