Following text contains part of story of The Children of Húrin depicted in the movie or necessary to comprehend it.
Húrin, father of Túrin, was taken captive by Morgoth after the Battle of Unnumbered Tears. Because he refused to reveal the location of secret city of Gondolin, he was chained to a rock and his house was cursed.
The land where Túrin resided with his mother, Morwen, was quickly seized by Easterlings. Morwen was concerned with Túrin’s safety and sent him away to elven settlement in the woods of Doriath. Morwen could not go there, because she was pregnant.
Morwen gave birth to a girl she named Niënor and the girl grew quickly. Túrin also became man. Because of unfortunate turn of events and his stubborn nature, he became unwanted in Doriath and wandered through the wilderness until he settled into another elven strongold, Nargothrond. Finduilas, daughter of the Nargothrond king fell into love with him, but he did not reciprocated her love.
Morgoth attacked. Túrin fought with orcs, but in the meantime Glaurung attached Nargothrond. Túrin came too late, when the orcs dragged captured elves to captivity, Finduilas among them. Glaurung froze Túrin with his gaze so Túrin could just look as the leves were dragged away. Then the dragon suggested Túrin that Finduilas suffers because of his inability to protect.
Túrin ran away to look for Finduilas, but he only found a group of hunters from Brethil, who told him that orce were dragging the elves through Brethil and when the hunters attached, the orcs killed all the elves, including Finduilas. They brought Túrin to the mound where Finduilas was buried. Túrin decided to stay with the hunters.
Túrin didn’t know that in the meantime Morwen and Niënor decided to look for him in Doriath, but they did not found him there, since he already departed. There they learned about fall of Nargothrond and that Túrin might have been there too. They went there together with elf Mablung and his group of hunters. But they found only Glaurung who covered the land by a dense fog where everybody got lost. Lonely Niënor found Glaurung and he bewitched her with his gaze, so when Mablung finally found her, she just stood there and did not react to his words. Morwen they lost altogether.
Mablung with the rest of the group led Niënor back to Doriath. When their camp was assaulted by a group of orcs, Niënor suddenly jumped up and ran away so fast, that the elves quickly lost trace of her.
Niënor ran through woods, flayed her clothing and ran through the forest naked till she fell completely exhausted. When she awoke, she lost her memory completely – she didn’t know who she is or where. She walked through the forest and she was amazed by just everything she saw. When she laid down again on a mound of Finduilad, Túrin passed by, found her and took her to the village.
Niënor was treated by a village elder, Brandir, who quickly fell in love with her. But Niënor has only Túrin in mind and Túrin Niënor, so they eventually got married, despite Brandir’s objections.
Shortly after the wedding, Niënor became pregnant. Then the message came that Glaurung left Nargothrond and is moving towards the village where Túrin and Niënor resided. Túrin decided that they should go out and face him, instead of waiting. And that he can do it alone with his Black sword Guthang. He only took two men with them. Niënor did not want to let him go, but he didn’t listen. Niënor did not want to sit and wait for Túrin and went to look after him. Lot of people from the village accompanied her.
Túrin decided the best strategy will be to wait when Glaurung will need to cross the river Teiglin, wait for him at the rocks and stab him from below. One of his men, Dorlas, was so afraid of water that he was unable to cross Teiglin, the second one, Huntor, was hit to head by a boulder when they climbed the rocks surrounding the river.
Túrin alone was successful, his magical sword wounded dragon greatly, the dragon jumped in pain to the other side of the river where he was dying. Túrin came after him, but when he pulled away his sword, dragon poison splashed his hand and Túrin went unconscious.
Niënor with the people from Brethil went to look after Túrin. When the darkness fell, they sat by the river. There Brandir caught up with them and led Niënor away. Niënor thought they are going to look after Túrin, but when she learned that Brandir does not intend to do it and that he rather wants to take her away, she yelled at him and ran away to look for Túrin on her own.
She found him, unconscious hand burned. She threder his hand, when Glaurung awoke the last time and told her, that she and Túrin are siblings and so that they committed incest. At that moment, Brandir came nearby and overheard everything. Shocked Niënor stood up, ran to the river and jumped into the waves.
Brandir, thinking Túrin is also dead, returned back to tell the folk of Brethil what just happened. On the way, he met Dorlas, they fought and Brandir killed Dorlas. In the meantime, Túrin awoke and came to the rest of the people just when Brandir was saying that Túrin and Niënor were siblings and that Niënor is dead. Túrin got furious and killed Brandir saying he is a liar.
Then he went to the mound of Finduilas and rested there only to be found by Mablung, who was searching for Niënor for past several years. Mablung confirmed that Niënor was really Túrin’s sister. Túrin understood that Brandir was no liar, ran to where Niënor ended her life and killed himself with Guthang.
When Húrin’s house was definitely discontinued, the doom was fulfilled and Morgoth released Húrin. Húrin wandered to the tombstone of Túrin and Niënor, where he found his wife, Morwen sitting there. She looked at him and died in his hands.