Arthur Dent has spent five years on prehistoric Earth. His cave stands where Islington will one day be, but no bus is due for two million years. Ford Prefect left four years earlier. Arthur talks to trees to keep hold of language, fails at gardening and wakes each morning with the shock of remembering where he is. One visitor briefly raised his hopes of rescue: an alien landed, insulted him and flew away. The encounter shows how isolated Arthur has become, and how little the wider Universe appears to care about his predicament.

That visitor is Wowbagger, made immortal by accident. Having exhausted the pleasures of living indefinitely, he has assigned himself an endless job: insult every inhabitant of the Universe personally and in alphabetical order. His itinerary turns the large question of what gives an unending life purpose into a filing problem. Arthur, facing a smaller but acute version of purposelessness, decides one morning that going mad might help him bear his solitude. Ford returns just as he announces the decision. Their reunion brings relief, along with Ford’s familiar ability to irritate him almost immediately.

Ford has detected a disturbance in space-time. It appears as a Chesterfield sofa drifting across a field. The two men chase it, jump aboard and land in the middle of the pitch at Lord’s during the closing stages of an England–Australia cricket match. Arthur briefly enjoys tea, mown grass and the familiar details of his former life. Then Ford points to the date on a newspaper: Earth is due to be demolished in two days. Arthur’s return home gives him no lasting shelter, and even the ordinary objects he carries seem to have changed during the journey.

At the ground, Ford spots a ship that the crowd overlooks because it is covered by a Somebody Else’s Problem field. Slartibartfast emerges and demands the urn containing the Ashes, insisting that it matters to the Galaxy’s safety. White robots then attack Lord’s, mimicking cricket strokes while hitting explosive balls. Arthur and Ford escape with Slartibartfast in a ship shaped partly like a small Italian restaurant. A sporting relic, a wandering sofa and a galactic attack now belong to the same story. The characters have scarcely had time to ask how they connect.

Slartibartfast’s ship runs on Bistromathics, calculations drawn from the unreliable numbers on restaurant bills: who ordered what, how many people ate and what each person is prepared to pay. The joke also powers travel through space and time. In a room of Informational Illusions, Arthur and Ford enter a presentation of the ancient Krikkit Wars. A lavish documentary introduces the Wikkit Gate, made of steel, wood and Perspex pillars supporting gold and silver bails. The grand music and salesmanship make the account hard to take at face value, even as its underlying events become urgent.

Krikkit lies inside a dust cloud that conceals every star from its inhabitants. They have never asked whether they are alone in the Universe because they do not know there is a Universe to be alone in. A crashed alien ship gives them the means to build a ship of their own, with a speed Ford finds impossible to credit. Its pilots cross the cloud and see the stars for the first time. Their response to this discovery is to decide that everything beyond Krikkit must go. The blank sky has shaped what they can imagine; seeing past it does not immediately enlarge their sympathies.

Their decision becomes a war fought by huge fleets and lethal white robots. Krikkit forces strike many worlds at once, seize resources for further construction and destroy the worlds they have raided. The account insists on an unsettling combination: the people can be pleasant in ordinary life while supporting the obliteration of every other life form. Their domestic songs and their military purpose occupy the same history. The destruction is too large to be treated as a harmless misunderstanding, yet the speed with which an enclosed world acquires vast technology and a single murderous purpose remains conspicuously strange.

After the Galaxy wins, Judge Pag orders Krikkit and its sun sealed inside an envelope of Slo-Time. They are to emerge only after the rest of the Universe has ended, receiving the solitude they sought. A lock on an orbiting asteroid controls the enclosure, and the Wikkit Gate serves as its key. A surviving Krikkit warship tries to seize that key. Ship and key are scattered through space-time rather than lost forever. Slartibartfast traces several of the pieces as they reappear. The white robots are collecting them, and the historical account has become an immediate race to keep the planet locked.

The search for the key sends the story across several places and lives. On a marsh world, the Krikkit robots take an artificial leg from Marvin, who has spent more than a million and a half years walking in a tiny circle. Aboard the Heart of Gold, they seize the gold bail embedded in its Improbability Drive. Zaphod Beeblebrox confronts them and is shot. Parts of an ancient symbol have resurfaced as a prosthesis, a ship component and other objects with quite different uses. That disguise makes the pieces difficult to identify and the lock difficult to defend.

Slartibartfast traces the silver bail to a party that has lasted four generations. Its flying building raids the planet below for supplies and has helped ruin the land. Trillian is there after teleporting away from Zaphod without setting a destination. Arthur encounters her among the guests and meets Thor as well. The robots arrive before Slartibartfast’s group can secure the bail. They take the award containing it and badly damage the party. Arthur challenges Thor, then uses the moment when Thor steps outside to escape with the others. The pursuit of a small metal piece passes through a social event that has itself become a sustained form of destruction.

Arthur’s route to the party has already been interrupted by Agrajag, who lures him into a Cathedral of Hate. Agrajag says he has been reincarnated repeatedly as creatures that died through encounters with Arthur, including the rabbit whose skin became Arthur’s bag and a bowl of falling petunias. Arthur denies persecuting him intentionally. In trying to restrain Agrajag, he nevertheless causes his death again. Arthur flees an ensuing landslide and, distracted while falling, begins to fly as the Guide earlier described. Flight offers him a rare sense of delight, although trying to think too hard about how he does it makes him fall.

Trillian, meanwhile, studies another history in the Room of Informational Illusions. Hactar, a computer once ordered to build a weapon that could destroy the Universe, had put a flaw in the bomb to prevent its use. Its makers pulverized it. The supplied passages set this account beside the history of Krikkit without yet establishing the connection between them. They also show the damage done by time travel: objects return in unexpected places, a poet’s work acquires a disputed origin and a cathedral disappears from history altogether. Following the key means working with traces whose origins and routes through time cannot be taken for granted.

The group reaches the lock’s asteroid too late to stop the robots inserting the assembled key. The asteroid passes through the dust cloud, the Slo-Time enclosure opens and the robots destroy the lock. The immediate means of sealing Krikkit again is gone. Ford and Trillian find Zaphod alive, though injured: the robots had carried him away and repeatedly knocked him unconscious. After the lock’s destruction, he once more has the gold bail. It and the wooden pillar survived intact. Slartibartfast’s attempt to keep the planet enclosed has failed, but opening the enclosure does not yet establish what every newly released Krikkiter will choose to do.

On Krikkit, the visitors find a divide between pastoral ground below and war zones suspended high in the sky. When inhabitants surround them, the encounter does not become the expected execution. These Krikkiters worry about universal destruction, the balance of nature and what would happen to their sport. One young man acknowledges that a small bomb might destroy everything, yet struggles to explain why they must use it. Trillian tells him he need not do so and asks to meet those leading the war zones. The conversation gives the planet’s inhabitants thoughts and doubts that the earlier account of their campaign could not contain.

The distinction grows sharper as Zaphod infiltrates a war command centre above the planet. He hears that commanders there are largely untouched by the uncertainty spreading among people on the ground. He also hears that the robots have become listless about the war. The final supplied excerpt begins to describe Marvin connected to the central core of the Krikkit War Computer, then breaks off in the middle of a sentence. The story has brought the bomb, the command structure, the robots and the possibility of refusal into the same place. These passages do not yet show how their confrontation ends.

The evidence supplied here stops before the novel’s ending. It supports the opening of Krikkit and the first visible resistance to its destructive purpose, but gives no basis for stating what happens to the bomb, what Marvin ultimately does or how the planet’s fate is settled. What is already clear is the pressure at the centre of the plot: a world first responds to discovering others by seeking to erase them, while some of its inhabitants begin to question the order they have inherited. Arthur, so often carried into events he barely understands, discovers that even a fall can change direction. The resolution remains beyond the supplied text.