Earthman and Englishman Arthur Dent awakens in his home in the West Country to discover that the local planning council is trying to demolish his house to build a bypass, and lies down in front of the bulldozer to stop it.

The Vogons, the callous race of civil servants running the fleet, announce that they have come to demolish Earth to make way for a hyperspace expressway, and promptly destroy the planet.

Meanwhile, Zaphod Beeblebrox, Ford's "semi-cousin" and the President of the Galaxy, steals the spaceship Heart of Gold at its unveiling with his human companion, Trillian.

In the tunnels, Zaphod reveals that his actions are not a result of his own decisions, but instead motivated by neural programming that he was seemingly involved in but has no memory of.

On the surface, Arthur is met by a resident of Magrathea, a man named Slartibartfast, who explains that the Magratheans have been in stasis to wait out an economic recession.

This computer was the planet Earth, which was constructed by the Magratheans, and was five minutes away from finishing its task and figuring out the Ultimate Question when the Vogons destroyed it.

The mice reject as unnecessary the idea of building a new Earth to start the process over, deciding that Arthur's brain likely contains the Ultimate Question.

The group manages to escape when the planet's security system goes off unexpectedly, but immediately run into the culprits: police in pursuit of Zaphod.

The police corner Zaphod, Arthur, Ford and Trillian, and the situation seems desperate as they are trapped behind a computer bank that is about to explode from the officers' weapons firing.

Suspicious, Ford discovers on the surface that Marvin became bored and explained his view of the universe to the police officers' spaceship, causing it to commit suicide.

Also by arrangement with Dove, ISIS Publishing Ltd produced a numbered exclusive edition signed by Douglas Adams (ISBN 1-85695-028-X) in 1994.

However, Adams got into disputes with the BBC (accounts differ: problems with budget, scripts and having Alan Bell involved are all offered as causes) and the second series was never made.

The main cast was the same as the original radio series, except for David Dixon as Ford Prefect instead of McGivern and Sandra Dickinson as Trillian instead of Sheridan.

The Hitchhiker's Guide to the Galaxy was adapted into a science fiction comedy film directed by Garth Jennings and released on 28 April 2005 in the UK, Australia and New Zealand and on the following day in the United States and Canada.

When Elon Musk's Tesla Roadster was launched into space on the maiden flight of the Falcon Heavy rocket in February 2018, it had the words DON'T PANIC on the dashboard display and carried amongst other items a copy of the novel and a towel.