In a future post-apocalyptic Earth in the year 2293, the human population is divided into the immortal “Eternals” and mortal “Brutals.” The Brutals live in a wasteland, growing food for the Eternals, who live apart in “the Vortex,” leading a luxurious but aimless existence on the grounds of a country estate. The connection between the two groups is through Brutal Exterminators, who kill and terrorize other “Brutals” at the orders of a huge flying stone head called Zardoz, which supplies them with weapons in exchange for the food they collect. Zed (Sean Connery), a Brutal Exterminator, hides aboard Zardoz during one trip, temporarily “killing” its Eternal operator-creator Arthur Frayn (Niall Buggy).
Arriving in the Vortex, Zed meets two Eternals — Consuella (Charlotte Rampling) and May (Sara Kestelman). Overcoming him with psychic powers, they make him a prisoner and menial worker within their community. Consuella wants Zed destroyed immediately; others, led by May and a subversive Eternal named Friend (John Alderton), insist on keeping him alive for further study.
In time, Zed learns the nature of the Vortex. The Eternals are overseen and protected from death by the Tabernacle, an artificial intelligence. Given their limitless lifespan, the Eternals have grown bored and corrupt. The needlessness of procreation has rendered the men impotent and meditation has replaced sleep. Others fall into catatonia, forming the social stratum the Eternals have named the “Apathetics.” The Eternals spend their days stewarding mankind’s vast knowledge—through a voice recognition-based search engine—baking special bread for themselves from the grain deliveries and participating in communal meditation rituals. To give time and life more meaning the Vortex developed complex social rules whose violators are punished with artificial aging. The most extreme offenders are condemned to permanent old age and the status of “Renegades.” Eternals who somehow managed to die, usually through some fatal accident, are then reborn into another healthy, synthetically reproduced body that is identical to the one they just lost.
Zed is less brutal and far more intelligent than the Eternals think he is. Genetic analysis reveals he is the ultimate result of long-running eugenics experiments devised by Arthur Frayn—who is Zardoz—who controlled the outlands with the Exterminators, thus coercing the Brutals to supply the Vortices with grain. Zardoz’s aim was to breed a superman who would penetrate the Vortex and save mankind from its hopelessly stagnant status quo. The women’s analysis of Zed’s mental images earlier had revealed that in the ruins of the old world Arthur Frayn first encouraged Zed to learn to read, then led him to the book The Wonderful Wizard of Oz. Zed finally understands the origin of the name Zardoz—Wizard of Oz—bringing him to a true awareness of Zardoz as a skillful manipulator rather than an actual deity. He becomes infuriated with this realization and decides to plumb the deepest depths of this enormous mystery.
As Zed divines the nature of the Vortex and its problems, the Eternals use him to fight their internecine quarrels. Led by Consuella, the Eternals decide to kill Zed and to age Friend. Zed escapes and, aided by May and Friend, absorbs all the Eternals’ knowledge, including that of the Vortex’s origin, to destroy the Tabernacle. While absorbing their knowledge Zed impregnates May and a few of her followers as he is transformed from a revenge-seeking Exterminator, his subsequent efforts to give the Eternals salvation by bringing them death are in essence acts of mercy. Zed helps the Exterminators invade the Vortex and kill most of the Eternals—who welcome death as a release from their eternal but boring existence. May and several of her followers do escape the Vortex’s destruction, heading out to bear their offspring as enlightened but merely mortal beings among the Brutals.
Zardoz ends in a wordless sequence of images accompanied by the sombre second movement (allegretto) of Beethoven’s Seventh Symphony, snatches of which are heard throughout the film. Consuella, having fallen in love with Zed, gives birth to a baby boy within the remains of the giant stone head. In matching green suits, they sit with the boy standing between them, who matures as they age in a series of dissolves. The youth leaves his parents, who take hands and grow very old, eventually decomposing into skeletons and finally vanishing. Nothing remains in the space but painted handprints on the wall and Zed’s Webley-Fosbery revolver