In 35,000 BC, a small Cro-Magnon child named Ayla is orphaned during an earthquake. One day, Ayla crawls into a cave to escape being killed by a lion. Soon, Iza, a Neanderthal medicine woman and member of the Clan of the Cave Bear, sees Ayla sprawled on some rocks, and discovers that she is alive. Brun, the Neanderthal Clan leader, orders Iza to ignore the strange golden-haired toddler, but she says that bird spirits encourage her to rescue the child. Iza and her brother, Creb, a holy man, adopt Ayla, and teach her their language. Other Clan members fear Ayla because she comes from an unknown tribe, and represents a negative spirit that will prevent them from finding a cave before winter comes. However, after a male Clan member reprimands Ayla for touching his spear, she runs away and finds a cave where the Clan can take shelter. The Clan lives in the cave for many years. Iza and Creb raise Ayla as part of their family, but she is slow to learn certain Clan ways. Broud, Brun’s son and the up-and-coming leader of the Clan, reprimands her for not being subservient. When Broud becomes a Clan hunter, Iza worries that Ayla will be in danger because of his fear and jealousy. Creb searches for a special totem to protect Ayla. He prays on the mountaintop, and has a vision of a mountain lion. Elsewhere, Clan hunters surround a musk ox and kill it. Later, Creb, dressed in ceremonial bearskins, gives Broud credit for the kill. Then, Creb presents Ayla with an amulet, saying that her protective spirit is the cave lion. Broud protests that the spirit is too strong to be given to a woman, but Creb silences him. Ayla grows strong and tall. She helps other Clan members catch fish in the river with her bare hands, but Broud disapproves of everything she does. Iza decides to teach Ayla the healing arts so that her place in the Clan will be assured once Iza and Creb are no longer around to protect her. One day, Ayla is allowed to heal a Clan member, and he is grateful. Meanwhile, a female Clan member delivers a stillborn baby. After the baby is buried, Iza explains that the spirits called for the child, and this comforts the child’s mother. Ayla asks if the spirits will give her a baby, but Iza responds that Ayla’s cave lion sign is too strong, and she will not have a child, which makes her sad. Later, Ayla sees her reflection in a pond, and realizes how different she is from the rest of the tribe. Hiding in the forest, Ayla watches male Clan members practice their hunting skills. She touches a sling left behind, even though she knows the punishment for a woman for such an action is death. Later, Broud hits Ayla for not bowing before him, but Brun tells him he cannot be a leader if he strikes his people. One day, as Ayla gathers berries and herbs in the forest, Broud rapes her. After she recovers, she finds a small cave where she can hide from him. She also practices with the forbidden sling, until her aim is accurate and she can hurl stones great distances. At mealtime, Ayla is not hungry, and Iza discovers that Ayla is pregnant. Broud rapes Ayla in front of other female Clan members, but she has learned not to react, and he is frustrated and leaves. Soon, the Clan settles in the forest, and is surrounded by a pack of wolves. As the men grab their weapons, a wolf carries off a Clan child named Brac, and Ayla stops it with her sling. Later, she is punished with banishment from the tribe, and considered an evil spirit. Even Iza and Creb ignore her. In the forest and her small cave, Ayla fends for herself, while her family mourns her loss. Later, Ayla goes into labor, and gives birth to her baby. She and the baby eat food that she hunts. When her exile is over, Ayla returns to the Clan with her baby, Durc. Broud thinks the baby is a burden and should be killed, but Creb pleads to spare Ayla and her child. Ayla is also pardoned and given permission to be a woman hunter. Later, Iza gives Ayla a medicine bowl that belonged to her mother. She is ailing and does not have the strength to travel to the Clan Gathering, but insists that Ayla go and find a mate. There, Ayla meets an admirer, and must relinquish her bowl to Creb because the other elders fear she is different. Soon, Ayla and Durc watch tribal hunters fight off a bear. When Ayla rushes to save a wounded warrior the bear comes after her. Ayla’s admirer attacks the bear, but is killed, and Broud savages the creature. Later, Creb conjures a magic fire that allows Ayla to see a vision. It tells her that her destiny involves leaving the Clan, but she cannot do it while Durc is young. Still, she waits for a sign. Later, Iza tells her that it is time for her to go and find her own people. The spirits have said it is so. Soon, Iza dies, and Brun decides to make Broud the leader of the Clan. Broud announces that he will take Ayla as his wife and Durc as his son. He also banishes Creb, but Ayla argues that Creb will die if he leaves. When Broud insists, Ayla pulls out her sling, and fights with Broud like a man. Brun interrupts the fight, telling his son that Ayla is a spirit and she has won. Broud is disgraced as Brun rips the warrior-leader necklace from his throat. Ayla tells her son that she loves him, and that they are one spirit. Then, Creb tells her to walk with the cave bear. She knows that her son will become the next leader of the Clan, but she sets forth to find her own people. The time is right. She is not afraid, and is propelled by the strength of her own spirit.