The film begins with a stand-alone 17-minute supporting feature entitled The Crimson Permanent Assurance (directed by Terry Gilliam). Set in London, England in present day 1983, a group of elderly office clerks in a small accounting firm rebel against their emotionlessly efficient, yuppie corporate masters. They commandeer their building, turn it into a pirate ship, and sail into a large financial district, where they raid and overthrow a large multinational corporation (before ultimately sailing to the edge of the earth and falling off).
The film proper consists of a series of distinct sketches, broken into seven chapters.
Part I: The Miracle of Birth
A woman in labour is taken into a hospital delivery room, where she is largely ignored by doctors (John Cleese and Graham Chapman) and nurses, who are more concerned with using the hospital's most expensive equipment to impress the hospital's administrator (Michael Palin). The woman in labour notices that hospitals are changing, with "lots and lots of machinery".
The Miracle of Birth Part II - The Third World In Yorkshire
A Roman Catholic man (Palin) loses his employment. He goes home to his wife (Terry Jones) and an impossible number of children, where he discusses the church's opposition to the use of contraception, leading into the musical number "Every Sperm Is Sacred". Watching this unfold, a Protestant man (Chapman) proudly lectures his wife (Eric Idle) on their church's tolerance towards contraception and having intercourse for fun, although his frustrated wife points out that they never do.
Part II: Growth and Learning
A schoolmaster (Cleese) and chaplain (Palin) conduct a nonsensical Anglican church service in an English public school. The master lectures the boys on excessively detailed school etiquette regarding the school cormorant, and hanging clothes on the correct peg. In a subsequent class, the schoolboys (Idle, Palin, Jones, Chapman, and others) watch in boredom as the master gives a sex education lesson, by physically demonstrating techniques with his wife (Patricia Quinn). Later, a team of boys is beaten physically and on the scoreboard in a violent rugby match against the masters; the scene then match cuts to Part III.
Part III: Fighting Each Other
A World War I officer (Jones) attempts to rally his men (Chapman, Gilliam, Palin, Idle, and Cleese) to find cover during an attack, but is hindered by their insistence on celebrating his birthday, complete with presents and cake.
A blustery army RSM (Palin) attempts to drill a platoon of men but ends up left alone when he excuses them one by one to pursue leisure activities.
In 1879, during the Anglo-Zulu War in Natal, a devastating attack by Zulus is dismissed due to a far more pressing matter: one of the officers, Perkins (Idle), has had his right leg bitten off during the night. The military doctor (Chapman) hypothesises that, despite not being native to Africa, a tiger might be the perpetrator. Ainsworth (Cleese), Packenham-Walsh (Palin) and a sergeant (Jones) form a hunting party, which encounters two suspicious men (Idle and Palin) dressed in two halves of a tiger suit, who attempt to assert their innocence through a succession of increasingly feeble excuses to explain why they are dressed as a tiger.
The Middle of the Film
A woman (Palin), as if on a talk-show called "The Middle of the Film", introduces a segment called "Find The Fish" a brief surreal piece in which a drag queen (Chapman), a gangly long-armed man (Jones), and an elephant-headed butler eerily challenge the audience to find a fish in the scene.
Part IV: Middle Age
A middle-aged American couple (Idle as the wife and Palin as the husband) heads to a dungeon-themed Hawaiian restaurant at a holiday resort. They are presented with a menu of conversation topics by their waiter (Cleese), and choose philosophy and the meaning of life. Their awkward and generally uninformed conversation quickly grinds to a halt, and they send it back, complaining "This conversation isn't very good."
Part V: Live Organ Transplants
Two paramedics (Chapman and Cleese) arrive at the doorstep of Mr. Brown (Gilliam), a card-carrying organ donor, to claim his liver. He protests on the basis that he is not dead, but is nonetheless gruesomely operated on against his will. Cleese's paramedic unsuccessfully attempts to chat up Mrs. Brown (Jones), then requests her liver as well. She initially declines, but after a man (Idle) sings a song about man's insignificance in the universe ("The Galaxy Song"), she agrees.
In a large corporate boardroom, a businessman straightforwardly summarises his two-part report on the meaning of life: that the human soul must be "brought into existence by a process of guided self-observation", which rarely happens because people are easily distracted; and that "people aren't wearing enough hats." This is followed by an attempted takeover of the building by the Crimson Permanent Assurance from the short feature.
Part VI: The Autumn Years
A posh restaurant (complete with a pianist played by Idle, singing "The Penis Song" à la Noël Coward), is visited by Mr. Creosote (Jones), a morbidly obese man in his autumn years. Creosote swears at the unflappable maître d' (Cleese), vomits copiously, and consumes an enormous meal and a huge quantity of beer and wine to the disgust of other patrons. After he has finished, the maître d' offers him a small after-dinner mint; despite initial resistance, Creosote eats it then explodes, showering the restaurant with human entrails and vomit.
Part VI-B: The Meaning of Life
Afterwards, two of the restaurant's staff clean up the mess left behind by the late Mr. Creosoto and offer their own thoughts on the meaning of life. The maître d' converses with cleaning lady Maria (Jones). The waiter Gaston (Idle) leads the viewer to the countryside where he was born, and explains that his mother encouraged him to notice the beauty of the world and love everyone. Realising that the audience is unamused, he angrily dismisses them and walks off.
Part VII: Death
A condemned man (Chapman) is allowed to choose the manner of his execution: being chased off the edge of a cliff by a horde of topless women.
A depressed autumn leaf "commits suicide" by falling off its tree. Distraught, his wife and children quickly do likewise, followed by the rest of the tree's leaves simultaneously. (Animated segment)
The Grim Reaper (Cleese) visits an isolated country house, and finds himself invited into a dinner party. Not knowing who he is, the dinner guests spend a lot of time arguing with him before finally being told they've all died from eating contaminated salmon mousse. Their souls leave their bodies, and they follow the Grim Reaper to Heaven.
The dinner guests arrive in Heaven, a bright Las Vegas-style hotel where every day is Christmas. In a large auditorium filled with characters from throughout the film, a cheesy lounge singer resembling Tony Bennett (Chapman) performs "Christmas in Heaven", while bare-breasted women wearing Santa Claus costumes perform an elaborate dance number.
The End of the Film
The hostess from "The Middle of the Film" is handed an envelope containing the meaning of life, and casually reads it out: "Try and be nice to people, avoid eating fat, read a good book every now and then, get some walking in, and try and live together in peace and harmony with people of all creeds and nations." She retorts that "gratuitous pictures of penises" and other meaningless controversies would do a better job at bringing the audiences into the cinema, and bitterly announces the closing credits.