In the opening number we see two tribes facing each other: the Kogallisk, servants of the moon who live on a great mountain and possess the secret of fire, and the Pana, servants of the sun who live nomadic lives and yearn to know the secret of fire. The Oroznah, an aged mystic, believes that a long night is coming (where the sun will not rise for a hundred years) and that the two tribes will need to unify and cooperate to survive. The Kogallisk and the Pana meet in the sacred forest as they do once every year to trade goods in preparation of the upcoming winter. The Oroznah leads the ceremony where the leading families of each tribe exchange the goods they have brought to trade. Koogalisk can forge metals and Pana are incredible hunters.

Chaos erupts when Mohr, a young leader of the Pana, and Ayla, heir of Tonah leader of the Koogalisk, accidentally touch, they are almost to fight but the Oroznah reminds them that their truce forbids any violence in the forest. As soon as she leaves, Tahl asks Tonah once again to share the secret of fire with his people, they need it to survive the winter and the long night, but she refuses as always. This is the law. Rooh, a clever yet scheming member of the Kogallisk, belittles the Pana, but Ayla, can only think of her illicit, fleeting contact with Mohr. As they return totheir mountain, she wonders why things must stay the way they are. Mohr has remained in the forest to watch Ayla and has overheard her questioning the status quo. Back at the Pana camp, Caladar, Mohr’s hotheaded brother, teases Mohr about the Oroznah’s prediction of a natural disaster. Mohr believes what she has said and supports his father’s quest for peace with the Kogallisk (Caladar does not). Sindah, Mohr’s intended, pushes Mohr to accept things as they are, but Mohr feels something is changing, Mohr confesses his affection for Ayla to Sindah who fears for his safety and longs for his love. Mohr leaves the camp in search of Ayla.

Back in the forest, Ayla prays to the moon asking for a sign, Mohr appears and she sees that the Pana is not different from what the Koogalisk are. Realising that Mohr has never seen a fire, Ayla shows him how she can make one. When they finally part, Ayla runs into the Oroznah who tries to make her see that the long night is actually coming and soon. Ayla returns to the Kogallisk camp to witness the union of several couples and learns that she is betrothed to Rooh. Ayla confesses her true feelings to her mother, but Tonah argues that a Kogallisk and a Pana could never be together. Never.
Ayla sleeps, but her dreams tell that the long night is indeed coming and that she and Mohr are domed. When Mohr awakes her (he has risked his life by entering the Kogallisk camp) she begs him to go but he refuses. When Rooh sees Mohr there, he captures him and the rest of the Kogallisk keep Mohr prisoner. Sindah, who has followed Mohr, finds Ayla and together they free Mohr from Rooh’s prison. In their struggle to escape, Mohr accidentally kills Lordu, Ayla’s little brother. As she holds Lordu in her arms, Ayla sees that this is a result of her actions. The Kogallisk prepare Lordu for burial as Sindah and Mohr return to their camp.

Back at the Pana camp, Tahl and Utza (unaware of what has transpired) tease each other about the fact that they do not possess the secret of fire, when Sindah and Mohr arrive. Mohr proves he has learned how to make fire but regrets his actions at the Pana camp. When Mohr explains what happens, Caladar convinces Mohr to run away, knowing that the Kogallisk will be looking to avenge Lordu’s death. when Mohr leaves, Caladar reveals his true intent: to become the leader of the Pana and fight the war to end all wars. Meanwhile Tonah and Crohm grieve over the loss of their son as Ayla questions everything, including the fact that she still loves the man who killed her brother. Though they are separated, their hearts are one and so our hero and heroine wonder what they can do to stop the coming war and bring their people together. When Ayla begs Tonah to prevent the war, Rooh reveals the fact that Ayla has given Mohr her v-steel and the secret of fire. When Ayla is banished, he takes her place as leader of the Kogallisk troupes. Sindah wonders if Mohr will ever return to her and his people. But Mohr sits alone far away wondering if running away was the right thing to do for his people and how he can prove himself worthy of the love he desires. The Oroznah appears and shows Mohr the path of the sun and makes him realise the long night is coming now. Mohr runs to save his people and Ayla’s. But is he too late? The two tribes are fighting already. Through the chaos, Ayla sees that Tonah is about to kill Tahl. she throws herself in front of her mother’s spear. seeing an underhanded opportunity, Caladar attacks Tonah from behind, kill her instantly and without honour. The two tribes come together to give Tonah the proper burial atop a great pyre as Ayla says her goodbye. As they are about to finish, the sun sets for the last time in a hundred years. Ayla lights a fire and then shares it with everyone onstage until every face glows by firelight in the darkness of the long night. they set Tonah’s pyre alight and leave the forest in search of a new home as the Oroznah offers her blessing.