The tale begins with a captivating address from Arthur Frayn/Zardoz, who boldly claims to be immortal and mischievously questions if the viewers themselves are but characters in a fictional narrative. He poses the query: "Is God in show business too?"
Fast forward to the year 2293, the world is starkly polarized into two factions: the Brutals and the Eternals. The Brutals endure harsh, perilous lives, striving to cultivate crops and survive amidst the remnants of a crumbled civilization, referred to as the Outlands. Among the Brutals, the most elite are the Exterminators—men trained to control the populace by exterminating those deemed undesirable. These men gallop on horseback, venerating a colossal floating head—the idol of their deity, Zardoz. Instead of urging the believers to procreate, Zardoz chillingly declares that "the penis shoots seeds and makes new life to poison the earth with a plague of men," commanding the Exterminators to "go forth and kill." In alignment with this divine order, firearms and ammunition pour from the mouth of Zardoz.
Zed, played by Sean Connery, seizes one of these guns—a Webley-Fosbery semi-automatic revolver—and fires it directly at the camera. Accompanied by Beethoven's Seventh Symphony, the decapitated head drifts through the opening credits.
Inside this enigmatic stone head, Zed discovers heaps of grain and potatoes along with several Eternals in a surreal state of suspended animation, encased in plastic. Zed cleverly manages to stow himself away, but the tranquility is abruptly disrupted when he encounters Arthur Frayn and instinctively shoots him. Injured, Frayn floats away, exclaiming, "without me you are nothing... how pointless!"
The head finally descends into the domain of the Eternals—specifically, Vortex Four. As Zed roams about, he stumbles upon a community reminiscent of a farming utopia filled with hydroponically cultivated vegetables, a mill, and a bakery. He ventures into the greenhouse and finds a room adorned with evolutionary diagrams and a shrine to Zardoz. Suddenly, a disembodied voice emanates from a crystal ring, which when shaken, reveals holograms illustrating the agricultural statuses of various regions in the Vortex, responding to Zed's inquiries with chilling detail.
While Zed is still trying to grasp his unfamiliar surroundings, he encounters May, a scientist who seeks to learn about this unusual Brutal. Their interaction takes a sudden turn when she uses telepathy to blind Zed momentarily, intrigued by his presence. A debate ensues between May and Consuella, a community leader who sees Zed as a perilous anomaly that could threaten their stable existence.
Ultimately, a vote is held among the Eternals regarding Zed's fate, with the majority opting to study him for a limited period, finding the depiction of Zed’s violent past both disturbing and strangely alluring. Friend, a cynical Eternal, is assigned to monitor Zed's actions. Their relationship unfolds as Friend attempts to unveil Arthur Frayn's whereabouts through telepathic means to no avail.
As Zed is dragged deeper into their peculiar society, he bears witness to their bizarre customs, such as the eerie gathering of Renegades, individuals punished for their transgressions by being aged, and the Apathetics, who exist in a state of lethargy, all gathered in a community that must feed these unproductive elements. Each encounter reflects the Eternals' stagnation and inability to cope with mortality, while Zed's presence stirs unrest among them. Observing a trial of George Saden led by Friend, Zed is exposed to the harsh realities of their judicial system, where justice seems profoundly detached from accountability.
As tensions rise, Zed's very existence begins to unravel the fabric of the Eternals' world. He witnesses a long-held belief system unravel as the community grapples with their own suppressed desires brought forth by Zed's animalistic nature. Amidst this turmoil, May finds herself attracted to Zed, leading to an embrace interrupted by Consuella's accusatory confrontation.
In an unexpected turn, Zed learns about the orchestrated framework of their society, realizing that his arrival was meticulously planned by Arthur Frayn, who sought to control the Brutals through genetic manipulation. As revelations unfold, Zed delves into the deeper secrets of the Vortex, seeking to destroy the Tabernacle, an AI entity overseeing their community, only to discover its insidious roots within the very crystal in his possession.
As chaos erupts within the Vortex, stirred by Zed’s actions, the Exterminators invade, leading to a cataclysmic transformation where emotions surge. Zed seeks solace with Consuella, and together they face the collapsing structures of society, ultimately confronting their own nature and the inevitable cycle of life and death that they had desperately tried to escape.
Amid Beethoven's powerful strains, Zed and Consuella grow old together, proving that even in a world torn apart by conflicting ideologies, the essence of humanity persists. As they face the end, they confront the existential questions posed throughout their journey, affirming that they are indeed reflections of a shared experience shaped by the fragility of existence.
