After their epic journey across Europe, Ayla and Jondalar have reached his home, the Ninth Cave of the Zelandonii, the old stone age settlement in the region known today as southwest France. Jondalar's family greet him warmly, but they are initially wary of the beautiful young woman he has brought back, with her strange accent and her tame wolf and horses.

Cast out by the new leader of the Neanderthal clan that adopted her as a child, Ayla leaves those she loves behind and travels alone through a stark, open land filled with dangerous animals but few people, searching for the Others -- Cro-Magnons -- tall and fair like herself. The short summer gives her little time to look, and when she finds a sheltered valley with a herd of hardy steppe horses, she decides to stay and prepare for the long glacial...

The Earth is in the grip of a new Ice Age, and when twelve-year-old Eleanor's scientist mother disappears in the Arctic, Eleanor sets off on a dangerous journey to find her--and uncovers a mystery, a crime, and evidence that Earth has been visited by extraterrestrials.

Still trying to stop the evil Dr. Kron-Tox, Andrew, his cousin Judy, Thudd the robot, and Beeper find Uncle Al in the Ice Age, where they encounter prehistoric animals, birds, and people.

The reader's choices determine whether three friends will survive after being mysteriously transported back in time to when the climate was cold and saber-toothed cats and wooly mammoths roamed the land.