A Connecticut Yankee at King Arthur's Court recap

Factory superintendent Hank Morgan is knocked unconscious and awakens in sixth-century Camelot. Facing execution, he uses foreknowledge of an eclipse to pose as a magician, displaces Merlin, and becomes King Arthur's powerful minister. He quietly builds schools, factories, communications, and a loyal modern organization while ridiculing chivalry and challenging inherited privilege. Adventures with Sandy and with Arthur expose him to oppression, slavery, and the limits of both medieval institutions and his own reforming arrogance. After returning to his original era and then finding himself in Camelot again, Hank learns that civil war and the Church have overturned his system. He and a few followers use modern weapons to destroy England's knights at the Battle of the Sand Belt, only to become trapped by the devastation. Merlin puts Hank into a thirteen-century sleep. Back in the nineteenth century, Hank dies longing for Sandy and their child, while his manuscript preserves the catastrophic story.

A nineteenth-century American encountered near Warwick Castle gives the framing narrator a manuscript explaining his strange familiarity with Arthurian Britain. In it, Hank Morgan describes himself as a practical, combative superintendent at a Connecticut arms factory. After an employee strikes him during a fight, he wakes beneath a tree and is captured by the armored Sir Kay. Taken to Camelot, Hank realizes that he has somehow reached the sixth century. Arthur's court treats Kay's distorted account of the capture as credible, and Hank is condemned to be burned. The young page Clarence befriends him in prison. Remembering that a solar eclipse is due, Hank claims that he will darken the sun and uses the eclipse to terrify the court. Arthur spares him and makes him a powerful minister. Hank then destroys Merlin's tower with explosives, presenting technology as superior magic and securing his new public identity as the Boss.

Hank becomes the king's chief executive and begins a concealed program to transform the country. Because the established nobility and Church would resist direct reform, he founds schools and workshops that can train a new generation in modern skills and ideas. He also develops newspapers, communications, and industrial projects while allowing the public to understand them as wonders associated with his power. At a tournament he sees how spectacle and inherited status sustain the knights' authority, and he plans eventually to beat them on terms of his own choosing. When Alisande, usually called Sandy, asks Arthur's court for a champion to free imprisoned noblewomen, Hank accepts the assignment. He sets out in an impractical suit of armor, experiences the discomfort of knightly travel, and struggles to translate Sandy's romance-shaped explanations into ordinary facts.

Travelling with Sandy, Hank encounters people whose belief in enchantment is as powerful as any physical obstacle. Their journey takes them to Morgan le Fay, Arthur's sister, whose polished welcome masks arbitrary violence toward servants and prisoners. Hank uses his claimed magical authority to save some captives and sees more clearly how rank protects cruelty. At the supposed ogres' castle, he discovers that Sandy's monsters are merely swineherds and that the captive princesses are pigs; he nevertheless frames the outcome as a successful rescue. The adventure strengthens his attachment to Sandy while confirming his contempt for the stories by which Camelot interprets reality. Returning to his projects, he promotes practical education and uses manufactured marvels to contest the influence of traditional magicians.

Hank joins pilgrims travelling to a holy spring that has stopped flowing. The failure threatens the reputation of the local clergy and of Merlin, who cannot restore it. Hank's assistants secretly diagnose and repair the well, and Hank stages the result as a spectacular act of magic, complete with modern effects. He defeats Merlin in a public contest and uses the occasion to display the reach of the technical organization he has built across Britain. A newly founded newspaper offers another sign of rapid social change, though its style shows that machinery alone does not create judgment. Wanting Arthur to understand the lives of his subjects, Hank persuades the king to travel through the country in disguise. He must coach Arthur to suppress the habits and speech that reveal his rank, while the king begins encountering conditions normally hidden from the court.

Hank and the disguised Arthur visit a family devastated by smallpox and social neglect. The king overcomes his fear and helps the sick, showing personal courage even as the episode exposes the failures of the order he rules. They later stay with Marco, a poor freeman, and meet the prosperous blacksmith Dowley. Hank's detailed comparison of wages and prices punctures local claims that low pay proves prosperity. Before the travellers can return openly to power, they are denounced, captured, and sold into slavery. Arthur's sense of royal identity repeatedly puts them in danger because no one believes his claims. After harsh marches and punishments, they escape briefly but are recaptured and sentenced to hang. Hank reaches one of his modern installations by telephone, but he and Arthur remain in immediate danger as the execution approaches.

Sir Launcelot and other knights arrive on bicycles in time to save Hank and Arthur from execution. Back at Camelot, Hank defeats Sir Sagramor and a field of armored knights with a lasso and revolvers, publicly establishing the superiority of his methods. Three years later his reforms have spread, and he has married Sandy; they have a daughter. A journey abroad for the child's health removes him at the decisive moment. On his return, Arthur is dead, civil war has broken Camelot, and the Church's interdict has dissolved Hank's support. Clarence and a small loyal force retreat with him to a fortified cave. At the Battle of the Sand Belt, mines, electric wire, and rapid-fire weapons slaughter the attacking chivalry. The defenders win but are trapped amid the dead, and disease spreads. Merlin enters in disguise and casts a thirteen-century sleep over Hank before dying on the electric fence. Hank wakes in the nineteenth century. The frame narrator later finds him dying in delirium, calling for Sandy and their child as though they had only just left his room.

Civil war and an interdict destroy Hank's political position while he is away from Britain. He returns to find that most of his supporters have deserted, leaving Clarence and a small group of trained young followers to defend their works. From a fortified cave, they use an electrified fence, explosives, and rapid-fire weapons to annihilate the massed chivalry of England. The victory traps the defenders behind a barrier of corpses, where disease begins killing them. Merlin enters in disguise and casts a spell that will make Hank sleep for thirteen centuries, but accidentally touches the electric fence and dies. Hank awakens in his own century. In the frame narrative, the visiting stranger who has read Hank's manuscript finds him delirious and dying, mentally returned to Arthur's age and calling for Sandy and their child. His attempt to remake Camelot has ended in destruction rather than the democratic society he intended.