After the apocalypse, an Executioner kills his God.
Voice of Death - Reginald Jarman
In the year 2293 a group of Exterminators are gathered around their god Zardoz, which is a giant floating head. He tells them they were chosen to kill the Brutals and the gun is good while the penis is evil, because the penis produces more Brutals while the gun purifies the earth. He orders them to go forth and kill and throws up a bunch of rifles. Zed, an Exterminator, sneaks aboard Zardoz, and shoots Arthur Frayn who calls Zed foolish for shooting him for he could have taught him many things before Arthur flies away to his death. Zardoz lands in a valley with buildings and Zed leaves Zardoz. He walks around and explores the building complex and finds artifacts from the past and complex food and vegetable systems. He also sees Immortals walking around or standing still in trees. While searching a building, he finds a ring device that lists the surplus and needs of different vortexes and also acts as a form of encyclopedia, answering questions the wearer asks. He is about to shoot May when she uses mental powers to stun his mind, causing him to drop his revolver. She asks him what he knows about the Vortex and he tells her what Zardoz has told him. Zed is put on a table while May and Consuella watch his memories on a screen, including that Zardoz has taught them to use slavery to produce wheat. Consuella is disturbed by the use of slavery, however May reminds her that she eats the bread from the wheat. Consuella wants to kill Zed while May wants to study him. May asks her ring what happened to Arthur Frayn and it tells her he has died and is being reborn and a fetus appears in a nearby clear bag. May, Consuella, Friend, Avalow, George Saden, Star and a group of other Immortals are watching Zed's memories in a large open room. May and Consuella want to investigate what Arthur was doing and Friend reminds everyone no one else wanted to run the out lands. A vote is taken and it is decided Zed shall live for another three weeks so May can study him.
Friend takes Zed from his cage in the morning and then demands to know what happened to Arthur Frayn, which Zed refuses to answer, he then takes Zed to a warehouse of artifacts where Zed is to work when May is not studying him. May brings Zed into a triangular lab where she examines Zed physiologically. She is interrupted by the trial of George Saden who is on trial for exhibiting negativity which he calls constructive criticism. Zed learns from Friend that when an Immortal is convicted of a crime they are aged as punishment, but as there is no death the person just continues to look older as their crimes continue. Friend takes Zed to the area where the Renegades live, Immortals who have been aged to the point of senility. Friend is also told he must decide on the fate of George Saden and Friend votes for absolute acquittal. Friend next takes Zed to see the Apathetics, a disease that affects Immortals and causes them to be highly pliable and in a zombie like state. The final vote is tallied and George Saden is aged 5 years. During another meeting, Consuella discusses the cause of erections which she likens to aggression. She plays a series of images in an attempt to cause Zed to get an erection, however it is Consuella who ultimately causes Zed's erection. May continues to study Zed and learns he is a mutant with breeding potential and she again asks him how he came into the vortex and realizes he is superior to her and the other Immortals. She promises to keep the knowledge to herself if he makes no move to disrupt the society.
During dinner a debate erupts when Consuella accuses Friend of using Zed to do work he is supposed to do himself. Consuells again calls for the destruction of Zed. Another vote is taken and May is given seven more days to complete her study of Zed and then he will be terminated. A meditation is started and Friend tries to resist going to second level, which is a group meditation. Friend is deemed a renegade and is to be punished. Zed runs away and comes to the invisible shield of Vortex 4. He then goes to the home of the Renegades and finds a physically changed Friend who blames Zed for his fate. Friend urges the other Renegades to attack Zed. Zed asks Friend what he wants and Friend tells him he wants death for everything and Zed agrees to help him bring death. Friend tells Zed about the Tabernacle which is what keeps the Immortals alive. He takes Zed to meet a founding member of the Immortals and one who created immortality and the Tabernacle. The Old Scientist tells Zed to talk to May. Zed opens his memories to May and she learns of his mission to kill the Brutals. He tells of one day where he followed a masked Brutal who taught him things which changed him and he learned to read and then read as much as he could. May sees then that Zed murdered Arthur Frayn, who he knew was Zardoz, because he felt Arthur had betrayed them. Zed then explains how he got inside Zardoz. He explains he told the other Exterminators of the book he read the Wizard of Oz and how he learned they were worshiping a fake god, a man behind a curtain. Zed then admits to May he came for revenge. Consuella finds May about to have sex with Zed and accuses her of bestiality. She tries to use her mind powers on Zed and he resists until he becomes blind. Avelow finds and takes him and restores his vision. She understands that Zed is the one to kill everyone and she agrees to help him if he kills her. She explains the history of the Immortals who cut themselves off from the rest of the world during the apocalypse.
Consuella bring a large amount of Immortals who attack Zed but he is able to escape. He runs to the vortex walls and signs to some Exterminators outside the vortex wall. Zed is hiding when a group of Apathetics surround him and drain him of his vigor after an Apathetic takes sweat from him, licks it and then spreads it to the others. Zed continues to run and escape and is found by some Renegades who bring him to Friend. Disguised, he crosses paths with some Apathetics who stole his vigor and are now having sex. Friend takes Zed to May and she agrees to help. Zed is taught all of the Immortals knowledge by May, Avelow and Star in exchange for his seed. He figures out the use of a crystal will destroy the Tabernacle. Consuella finds Zed and realizes she has become what she accused him of while hunting him and they agree to stay together. Zed asks the Tabernacle a series of questions and realizes the Tabernacle is in the crystal, and Zed is transported inside the crystal. He is shown the faces of everyone he will destroy and shoots an image of himself, reemerging from the crystal. Zed returns with psychic powers which he uses to push away any attacking Immortals. He takes the crystal to the Old Scientist who tells him how to destroy the Tabernacle and the Old Scientist dies. The skull head of Zardoz then crashes into the ground. Zed gives May the crystal and tells her to let her sons and daughters to look into it and to head East out of the Vortex. Arthur Frayn admits to Consuella he and Friend worked together through careful genetic breeding to create Zed. Once the Immortals learn they can finally die, the fighting stops. Avalow leads a seance telling the Immortals death approaches and to make their farewells. Avelow asks Zed to kill her like he promised however he is changed and cannot. She is then shot by an Exterminator and the rest of the Immortals are killed by the Exterminators Zed had been communicating with. Zed takes May's hand and they run away. Friend and Arthur Frayn are both shot after Arthur does one last magic trick. In a cave Zed and Consuella have sex. Later Consuella has a son who eventually leaves them and then Zed and Consuella grow old and die leaving their marks on the world.