NOTE: This spoiler was sent in by Amaryllis.
The story begins with a voice over that explains that long ago there were a people who were hunters. Things were not going so well and the spirit woman was constantly asking the gods for a sign. The sign came when the hunters found a young girl with blue eyes. Her name was Evolet (Camilla Belle). The spirit woman touched Evolet's face and saw visions. After that, she said that all of Evolet's people had been slain by the 4-legged demons. She also said that the young girl would grow up to be the woman of the man who will lead their people. All of this will happen after the people's last hunt. At this time the main character D'Leh (Steven Strait) was a young boy. He noticed her Evolet from the first time she arrived at their village.
Meanwhile, D'Leh's father cannot wait for the fulfillment of the spirit woman's prophecy. He holds the white spear (which means he is the lead hunter) and gives it to his friend Tic Tic. He is off to search for answers that could help his people. Everyone thinks that he abandoned his people and the young children make fun of D'Leh because of it. He and Evolet grow closer because he is lonely like her.
Years later when they are adults, the voice over said that the hunters went out for the last hunt. Before the hunt, Tic Tic said that the one who kills the mammoth would hold the white spear and claim Evolet. D'Leh is still treated with little regard because his father was the coward, but is determined to win the white spear and the girl. During the hunt, all is going as planned when they capture one mammoth in their nets. However, the mammoth breaks free. Everyone is holding on gradually let go. D'Leh and Tic Tic are the last ones holding on. Tic Tic told him to let go. He said that his hand was stuck. The mammoth continues to drag him on and only dies when falls on D'Leah's spear. Only Tic Tic knows the truth and just gives D'Leh a look of disapproval when he asks for the white spear. D'Leh later gives it back. But Evolet is upset because she implied that he should have kept so they could be together.
During the night, the 4-legged demons come and ransack the village, kill people, and take some in chains. The 4-legged demons are actually warlord men on horses. One of the people taken is Evolet because one of the men is taken with her beauty. D'Leh is determined to follow and rescue his love. The spirit woman doubts that he is able to accomplish the task by himself. Tic Tic and another hunter agree to go with him. The spirit woman gives her blessing and uses her spirit powers to be with them. She feels their suffering during the journey.
They are able to follow the warlords over the mountains and into the forest. In the forest, D'Leah disregards the advice of Tic Tic and tries to free Evolet. As they try to make the escape, there are these giant man-eating birds that attack. In the end, the warlords capture Evolet and 2 of the others in D'Leh's group. Tic Tic is injured. D'Leh nurses him back to health while continuing to follow the warlords. One night he is out trying to kill some food and falls into a pit. Some time later he is awaken by the rain. He sees a saber-tooth tiger that is struggling not to drown. He wants to kill it but cannot since it is helpless. He frees the tiger and the tiger roars in his face can runs off.
The next day he and Tic Tic go into a village and begin to eat food that they see that is outside. Then the tribe of people appear and pull out their spears. There is a face off between the tribe and D'leh and Tic Tic. Meanwhile, the saber-tooth tiger appears and once again roars in D'Leh's face. He mentions to the tiger that they already know each other. Because this exchange fulfills an ancient prophecy in the village about the man that speaks to the tiger, they follow D'Leh to rescue their people. The warlords passed through and captured some of their people too.
All the tribes bad together following D'Leh to rescue their people. Someone mentions that the warlords use birds to fly to their destination. The birds are actually ships going down a river. D'Leh and the men travel on land to meet the warlords at the end of the river. There are thousands of people there that are being held captive to build giant pyramid for the "Almighty".
The "Almighty" is supposedly the god among them and commissions the build of the pyramid like tower in the Ancient city. He gives his approval or disapproval of the work being done on the pyramid. He calls for a sacrifice because he is not pleased with their progress. One of the men from D'Leh's village is killed. D'Leh infiltrates the slave camps to inform the people that they will overthrow the powers that be and release Evolet. After talking to a blind, wise man D'Leh learns that the "Almighty" is only afraid of the one who bears the mark of the hunter. He does not have this mark and so he is unsure if the enslaved workers will assist him with overthrowing the "Almighty". That night Tic Tic is killed in a scuffle with some of the guards from the Ancient city. He passes the white spear to D'Leh and encourages him to fulfill his destiny.
Meanwhile, the warlord has bought Evolet and is getting ready to claim her as his. With her in his arms, she takes his knife. She is stopped from killing him because priests or monk-like people come to take the warlord. They ask him why he did he steal from the "Almighty". Then they take the knife from her. When they do so, they see her hand and her scar is the mark of the hunter. Her scar matches a constellation. They run to tell the "Almighty" and he is understandably agitated because he is near his end.
The next day is the rebellion. D'Leh gets the mammoths that are doing the work to rampage. As a result all hell breaks loose. People who were getting whipped turn on their captors, beating and killing them. The priests or monk-like people tell the "Almighty" what is happening. He said they should tied up the girl because the hunter just wants her.
The hunters and ex-slaves are running towards the temple of the "Almighty" and D'Leh stops everyone because he sees Evolet tied up. The "Almighty" said that he can take her and leave everyone else. He says that he will agree to this bargain. Then he throws his spear and kills the "Almighty". Everyone sees that he is not a god as he claimed. While all the fighting is going on, D'Leh is looking for Evolet. The lovestruck warlord is determined to have her and is escaping with her on a horse. Evolet uses an arrow to stab him and they fall off. She runs towards D'Leh. The warlord shoots her with an arrow in the back and says that D'Leh will not have her either. D'Leh holds her and she breathes her last breath. But as she does that, the spirit woman gives Evolet her breath.
Evolet lives and D'Leh, his tribesmen return home. A man who was friends with D'Leh's father gives him some seeds for them to carry back to their land. This is so they will have food and not go hungry in lean times.
The movie ends with Evolet and D'Leh kissing in the sunset.