Act One

A camp in the Bashkir steppe, where a rich and wise woman, Baibisa Tankabika, rules an ancient clan after the death of her husband. She is known as wise and fair - everyone in the clan honors and respects her.
The life of the Baibisa passes in worries about the family and household chores: the youngest son Ishmurza is growing up, the middle son Akyeget, engaged to the beautiful Zubarzhat, is growing up; the eldest son Yulmurza, who is awaited by his young wife Shafak, is about to return from serving the king. And for the foundling Diuana, offended by reason, Tankabika will always find a kind word.
A wanderer Dervish passed through those places, stopped to rest at the camp, where the hostess is so welcoming and kind. Is her name Tankabika? Once upon a time he knew a beauty with such a name...
Life at the camp flows wisely and fairly - soon Akyeget, with his mother's blessing, will bring his young wife Zubarzhat into the house, and this is announced to the clan. And good news came that the war was over and, therefore, Yulmurza would return from the campaign... But this was not destined to come true. Yulmurza was not among the horsemen who returned from the war - he died a hero's death.

Act Two

The clan sacredly honors customs, adat - the covenants of the ancestors. Tankabika obeys the will of the elders of the clan in everything, and if the aksakals decided that Akyeget should take the widow Shafak as a wife, and Zubarzhat will have to be given to the young Ishmurza, then so be it.
Tankabika's heart is heavy - is Allah punishing her for the sins of her youth? Many years ago, the fruit of a vicious relationship of a baybisa was born - the wretched Diuana; the poor thing still lives among the steppe people as a foundling. It's been thirty years, but there is still no peace for Tankabika's soul: only she and Dervish, who hid this terrible secret, know about what was done.
The dervish, captivated by Shafak's beauty, threatens to reveal the secret of the baybisa to the aksakals and the whole clan if Tankabika does not give him his daughter-in-law, but is refused.

Act Three

For the third month, having submitted to the will of the elders, Shafak and Akyeget live in the same yurt. Shafak's days and nights drag on in melancholy and loneliness, because Akyeget's heart still belongs to Zubarzhat. Shafak is not the only one who knows where her husband spends his nights. The people of the clan also condemn the lovers, accusing them of adultery.
The dervish is full of sinful thoughts - he dreams of Shafak's love, and if she does not renounce her husband in front of people, then he threatens to extinguish the moon at midnight.
Unable to bear three days of separation from Akyeget, Zubarzhat comes to her beloved's tent. Akyeget no longer has the strength to hide. He decisively told his mother that from now on he will live only with his sweetheart.
But this is a mortal sin and a violation of adat! Isn't that why the Almighty punishes the family: cattle die, and people die of illness, and even the moon can go out over the country? If Akyeget and Zubarzhat do not repent and renounce their sinful love, everything can perish!
But Akyeget does not know the words of repentance. And let the world collapse, and let the light go out - he will not renounce his Zubarzhat!
The mother's heart is broken, but Tankabika's belated repentance is not heard by the enraged crowd.
The moon has gone out and the souls have been eclipsed. Akyeghet and Zubarzhat have been expelled from the clan - into oblivion, or into eternity, or into immortality? And a new moon is born...