The narrative begins over one hundred thousand years ago with Nu, a valiant Niokene caveman, who slays a saber-toothed tiger named Uu to win the hand of Nat-ul. Following an earthquake, Nu is sealed into a subterranean cavern where he falls into a state of suspended animation, preserved for millennia. In the early twentieth century, an American named Victoria Custer visits a remote African estate with her brother Barney. Victoria has long been haunted by vivid dreams of a prehistoric romance, a profound psychological connection that intensifies dramatically when underground tremors shake the region. The narrative shifts between the modern era and the primeval past, exploring themes of reincarnation and immortalism as the boundaries of time begin to blur.
When a massive earthquake shatters the ancient rock formations, Nu's subterranean tomb is opened and he is thrust back into consciousness. Awakening in a transformed world where magnificent prehistoric beasts have vanished, the caveman struggles to adapt to unfamiliar flora and fauna while striving to reconstruct his primitive weapons. Meanwhile, Victoria recognizes Nu in her dreams and senses his physical reality in the surrounding wilderness. Drawn by an irresistible ancestral imperative, she eventually slips away from the estate and ventures into the dangerous wilderness, guided by an innate, time-transcending bond that defies modern logic.
Nu's wanderings lead him to the modern bungalow, where he saves Victoria from a lethal lion attack using his stone-tipped spear before vanishing back into the jungle. This heroic act leaves behind tangible proof of his existence, deepening Victoria's conviction that her visionary romance is entirely real. Her subsequent disappearance into the wilderness initiates a desperate search by her brother Barney and other companions, who track both the mysterious caveman and the missing woman across untamed African terrain.
The plot escalates as a band of Arab slavers crosses paths with the search parties and captures Victoria, dragging her north toward distant territories. Both Nu and the modern rescue expedition pursue the caravan independently, navigating treacherous jungles, hostile tribes, and encounters with dangerous wildlife. Nu relies on his primordial survival instincts, tracking the kidnappers with a feral sharpness that confounds the modern hunters trailing the same path.
As the pursuers close in, Victoria manages to break free from her captors, only to find herself trapped between conflicting worlds. Nu intercepts her path and confronts her pursuers, ultimately defeating his rivals in brutal, visceral clashes that strip away the veneer of modern civilization. Confronted with the reality of her prehistoric lover, Victoria embraces her ancient identity as Nat-ul, choosing to abandon her civilized life and remain with Nu in the primal wilderness.
The final developments of the tale touch upon the philosophical implications of their union, acknowledging the immense temporal gulf separating their existences. Yet, their mutual devotion bridges the divide, suggesting that deep emotional and instinctual bonds can conquer even the passage of countless ages. The novel concludes with a poignant affirmation of their eternal connection, as they embrace a destiny far removed from the safe confines of modern society.
