The action takes place in the XIII century. in France, in Languedoc and Brittany, where the uprising of the Albigoys, against which the Pope organizes the crusade, is beginning to flare up. The army, designed to help the overlords, is moving from the north.
The play begins with a scene in the courtyard of the castle, where the watchman Bertrand, nicknamed Knight-Unhappiness, sings a song heard from the visiting juggler. The refrain of this song, telling about the hopelessness of life, the only way out of which is to become a crusader, is the lines: “The law of immortality is the heart – Joy – Suffer alone!” They will become “through” for the whole play.
Alice, the court lady, asks Bertrand to stop singing: her mistress, seventeen-year-old Izora, in whose veins Spanish blood flows, the wife of the owner of the castle, is not well.
The chaplain pestered Alice with indecent offers. She rejects him with indignation, but she does not
mind flirting with the page Aliscan. He, however, rejects it.
The doctor diagnoses Izore: melancholy. She sings a song about Joy-Suffering, understanding suffering as “joy with the sweet.” Playing chess with a page – and making fun of him. He scoffs at the unknown author of the song. Izora leaves. Alice seduces Alicana. Count Archimbaut, the owner of the castle, sends Bertrand to inquire: is the army far away rushing to the rescue? The chaplain, meanwhile, alludes to Madonna’s bad inclinations: she reads romance novels… The incoming doctor announces melancholy.
Izora asks Bertrand during his journey to find the author of the song. He agrees. The Count sends his wife into confinement – to the Tower of the Unwanted Widow.
In Brittany, Bertrand gets acquainted with the trumpet Gaetan, the lord of Traumenec: almost kills him during the fight, but soon they make peace and even have a friendly chat in the house of Gaetan. It is he who turns out to be the author of the cherished song. On the shore of the ocean, Gaetan teaches Bertrand to listen to the Voice of Nature.
Bertrand brings joyful news: he saw the troops. As a reward, he asks permission to sing at the festival juggler, whom he brought with him, and to release the Count’s wife from the Tower, where, judging by the conversations in the kitchen, they contain very strictly. And indeed: Izora grieves in captivity. Only dreams of a knight support her. Hopes are strengthened after the unfortunate takes on his account a love note addressed to Aliskan Alice, where a rendezvous is scheduled for the moonrise. In the meantime, Bertrand, in an interview with Gaetan, tries to understand: “How can suffering become a joy?” Izora, inconsolably waiting at the window, suddenly sees Gaetan – and, throwing him a black rose, loses consciousness from an overabundance of feelings. Count, thinking that imprisonment is the reason, announces release. In the courtyard of the castle Bertrand prays for the health of the unfortunate.
On the blossoming meadow at dawn Aliskan is angry with Alice, who did not come on a date, and again surrenders to dreams of Izora. Bringing Gaetana’s clothes to the juggler, Bertrand sees that black rose – and asks her for himself. On the May holiday, Aliskan is knighted. The minstrels compete in singing: the song about the war is rejected by the count, the song of love for the girls and the native land receives a reward. It’s Gaetan’s turn. After his song about Joy-Suffering, Izora is deprived of feelings. Gaetan disappears in the crowd. Recovering, Izora turns her attention to Aliskan. Meanwhile, the rebels are approaching the fortress. Bertrand fights better than everyone: his victory is due to him defending the fortress. But the Count refuses to admit the obvious, although it frees the wounded Bertrand from the night watch. Meanwhile, the unfaithful Alice agrees with the chaplain about a meeting at midnight in the courtyard, while Izora, exhausted in the spring from the heart emptiness, asks the watchman to warn about the arrival of unwanted guests during a meeting with her lover. In the role of that, Aliskan suddenly appears. But their date was discovered by Alice and the chaplain. The latter calls the count. At that moment, exhausted by wounds, Bertrand falls dead. With the sound of a fallen sword, he flushes Alicana. The young lover is running-and the count does not catch anyone entering the family’s quarters.