Rebecca, sometimes known as Remi, is Chobi's older sister. She is one of three children abducted by a UFO and transported to the Cretaceous period, sent there to learn about extinction and humanity's diminishing empathy for the environment. Rebecca navigates the Cretaceous wilderness alongside her companions, encountering diverse prehistoric creatures. She joins the group discovering a nest of Triceratops hatchlings. The children witness a Tyrannosaurus attack the nest, devouring all but one hatchling and killing the mother. This surviving hatchling, Zhu, imprints on the children, including Rebecca, seeing them as his foster family. As Zhu matures into adulthood, he retains a deeply affectionate bond with Rebecca and the others. Rebecca and her companions face relentless pursuit by the Tyrannosaurus throughout their journey, a pursuit that even follows them into the Stone Age. This vendetta ignites after Chobi injures the Tyrannosaurus's left eye. Rebecca witnesses Zhu's adult life and his climactic confrontation with the Tyrannosaurus. To protect Rebecca and the others, Zhu sacrifices himself, fiercely battling the Tyrannosaurus and ultimately plunging both over a cliff. The children's experiences conclude with their return to their own time, having witnessed the extinction of non-avian dinosaurs.