The Clan Of The Cavebear - Published 1980
Ayla's family is lost in an earthquake when she is five. She roams around, and becomes weak from not eating. By mistake, she comes too close to a cavelion's den and is attacked.
Iza, the healer of the Clan, finds her and heals her. Ayla lives with the Clan and learns their customs. Creb, the Mogur, adopts Iza and Ayla to his hearth and is like a father to Ayla. He is Iza's natural brother. Ayla isn't accepted by the clan at first, but she eventually is. This is because she is an "Other" [a Cro-Magnon]. She is given a totem spirit, too- The Great Cavelion. She has a son, and he is named Durc.
But with that, Ayla makes an enemy, Broud. When Broud became leader, everything changed. Iza and Creb both die, and the cave is caught in an earthquake. Goov becomes Mogur and is ordered by Broud to give Ayla the death curse. Unwillingly, the task is performed. Ayla leaves her son, never to see him again...
The Valley Of Horses - Published 1982
...Ayla travels looking for her people-the others. She finds a valley. It is almost winter, and she decides to stay. She accidentally kills a nursing horse while hunting and raises its young foul, who she names Whinney. She lives with and trains Whinney. Soon after, Ayla finds a baby cavelion, and names it Baby. Baby leaves and finds its own mate later, though.
Meanwhile, Jondalar and his brother, Thonolan, are traveling on a Journey. They find their way by following the Great Mother River. They meet may people. Thonolan marries a Sharamudoi, Jetamio, but she dies in childbirth. Thonolan no longer wishes to live, takes one too many chances, and has a run in with a cavelion...
Ayla is riding Whinney when she hears a scream! She finds two men, one alive and one dead. She realized a cavelion was attacking them, and recognized the cavelion-Baby. After saying hello to Baby, she goes back to the cave. She takes the man who is still alive back to her cave, who happens to be Jondalar. He eventually teaches her to talk. They, after a while, fall deeply in love. Ayla and Jondalar go on a hunting trip and while traveling, find the Mamutoi people...
The Mammoth Hunters - Published 1985
...Ayla and Jondalar meet the Mamutoi, a people who live in the cold climate and are known for hunting mammoths. The Mamutoi are very friendly and hospitable. Ayla and Jondalar get to know the people, and both of them grow fond of the cave. The people are very fond of Ayla.
After learning she was raised by flatheads [the clan], they aren't as open. This is because they don't believe that the flatheads/clan are humans. They do get over this, and they adopt Ayla. Ranec, who loves Ayla as much as Jondalar, gets in the way of Jondalar's relationship with her. In the end, Jondalar triumphs. Ayla and Jondalar decide to go back to his homeland, the Zelandonii's Ninth Cave.
They overcome many hardships during the winter they spend with the Mamutoi, and Ayla decides that it was a test from the Great Cavelion Totem...
The Plains Of Passage - Published 1990
...Ayla and Jondalar continue on their Journey to Jondalar's people. They meet many familiar faces, or at least they are to Jondalar. They meet the people of Jondalar's brother's wife. They meet other people Jon knew as well. While traveling, they also save a dying group of people from an evil ruler. Every time a new group of people was reached, they had to decide whether they wanted to stay with them or move on. They chose to keep going each time, and they eventually reach the cave of the Lanzadonii, where some of Jondalar's relatives live.
Joplaya, Jondalar's cousin, loved Jondalar. Unfortunately, Jondalar didn't know this. Joplaya decides to marry a man who loves her, even though she dosen't love him. Ayla sees this and thinks of Ranec. She is thankful she still has Jondalar. After saying goodbye, Jondalar and Ayla head out to the Zelandonii.
During their Journey, Ayla keeps having strange dreams about a cave. When they get to Jondalar's home, the cave is the one in her dreams! Ayla knows this is suppost to be her home. They are seen by Jon's sister and she shouts out that they are home...
The Shelters of Stone - Published 2002
Here is some kind of official publisher's summary...
THE SHELTERS OF STONE continues the story of Ayla, who lost her family to an earthquake and was raised by the people who called themselves the Clan of the Cave Bear. She arrives in the land of the Zelandonii, the home of Jondalar, the man she loves, but his people are wary of her and think of the Clan who cared for her as flatheads, animals that resemble people but who are not much smarter than bears. Ayla has brought with her two horses and a wolf, over which she has uncanny control. Though she tries to explain that she found the animals when they were babies and raised them as her own, to Jondalar's people - who have never tamed or domesticated animals - they seem supernatural and frightening. The story unfolds with those who want to cause trouble for Ayla, a woman who seems foreign and strange in this new land.