In a future far removed from our own, a pair of space travelers, Jinn and Phyllis, finds an intriguing message in a bottle drifting through the cosmos. The message, penned in "the language of the Earth," recounts an astonishing tale of intelligent humans. This narrative, written by a French journalist named Ulysse Mérou, reveals his extraordinary adventures on a distant planet where apes rule and humans are primitive.

A Journey to Betelguese

In the year 2500, Ulysse Mérou embarks on a daring expedition with Professor Antelle and Levain. Their destination is a planet orbiting the star Betelgeuse. The journey, funded privately, involves two years of space travel each way, although due to relativistic time effects, they expect to return seven centuries later by Earth's calendar. This voyage marks the beginning of Ulysse's incredible chronicle.

Arrival on a New World

Upon reaching the planet, the explorers are relieved to find a breathable atmosphere. As they step out, they encounter a small footprint by a lakeside. Their curiosity heightens when they meet Nova, a stunning, naked woman who initially fears them but soon engages with them, albeit nonverbally. Her inability to speak and the subsequent killing of their pet chimpanzee puzzle the group.

Human Savagery and Ape Civilization

The explorers' encounter with the wild humans turns dire when these primitives destroy their clothes and damage their spacecraft. The situation escalates with the arrival of a sophisticated hunting party of apes—clothed, articulate, and organized. The apes launch a brutal assault, capturing Ulysse and his companions for research and zoo exhibition.

Life in Captivity

Ulysse finds himself caged with Nova, and in time, they bond. Zira, the director of the research lab, notices Ulysse's intelligence and forms a platonic attachment to him. As they exchange languages, she becomes convinced of his extraterrestrial origins, though Zaius, a skeptic, dismisses Ulysse's intellect as mere mimicry.

The Hierarchy of Ape Society

In this world, the three ape species have distinct societal roles. Orangutans hold sway over "official science" yet are rigid and ceremonial. Chimpanzees are the innovators, while gorillas exert their strength in various utilitarian roles, from hunters to administrators. Ulysse learns these dynamics as he navigates his new reality.

A Plan for Public Revelation

Zira secures permission for Ulysse to explore the ape city under strict constraints. Despite the restrictions, Ulysse yearns for freedom but is cautioned by Zira of Zaius’s intentions to subject him to debilitating experiments. Her plan hinges on Ulysse showcasing his rationality with a public address at the upcoming national biological congress.

A Plea for Understanding

Ulysse prepares for his moment, aided by Zira’s clandestine provision of books and tools for learning. During a zoo visit, he encounters a diminished Antelle, now unable to communicate. At the congress, Ulysse delivers a compelling speech advocating for cooperation between species, which earns him liberation and acceptance among the apes.

Discovering a Lost Civilization

Now integrated into ape society, Ulysse struggles to teach speech to wild humans. He accompanies Cornelius to an archaeological dig, uncovering signs of a once-human civilization. A talking human-shaped doll suggests that the apes' predecessors may have been human. This discovery hints at a forgotten past where roles were once reversed.

The Threat of Intelligence

Nova’s pregnancy brings both joy and dread. If their child exhibits signs of intelligence, the apes may perceive it as a threat to their dominance, risking the lives of both father and child. Ulysse witnesses horrific experiments at the brain lab, where one woman regains ancestral memories, revealing a history of human decline and ape ascendance.

An Escape Plan

As Nova gives birth, Zira and Cornelius...