[1][2] Following directly on from the events of the previous book, it continues the misadventures of Arthur Dent, Ford Prefect, and the crew of the starship Heart of Gold on their journey across the universe and uncovering its bizarre mysteries.

A Vogon ship bribed by Gag Halfrunt and a group of psychiatrists, fearful that the discovery of the Ultimate Question will end their profession, intercepts and fires at them.

He transports Zaphod and Marvin to Ursa Minor Beta, the tropical home planet of the offices of the Hitchhiker's Guide's publisher Megadodo Publications, and leaves the others on the depowered ship in a black void.

The planet eventually became the site of the Total Perspective Vortex, a device that drives those who experience it mad due to showing them their insignificance compared to the infinite universe.

Left on his own, Zaphod eventually finds a long-abandoned spaceliner whose passengers have been forcibly kept in 900 years of suspended animation by the autopilot after the collapse of their civilization until a new one could develop to load the ship with lemon-scented paper napkins.

At the restaurant they meet Ford's old acquaintance Hotblack Desiato, a member of the rock band Disaster Area, which is known for making the loudest sound in the universe and only perform their concerts remotely from an orbiting spaceship.

During their dinner, Zaphod receives a telephone call from Marvin, who has been stranded on the planet for billions of years and is now working as a valet in the restaurant's parking lot.

Zaphod and Trillian find themselves back aboard the Heart of Gold under Zarniwoop's control, where he is using the ship's Improbability Drive to penetrate the Unprobability Field that is protecting the home planet of the Ruler of the Universe.

Meanwhile, Arthur and Ford find themselves aboard Ark Fleet Ship B, which is loaded with 15 million passengers from the planet Golgafrincham and is commanded by an inept captain who is only concerned with taking baths.

They return to the Golgafrinchans, only to find that they have been too preoccupied with trying to form council meetings about documentary-making, fiscal policy, searching for hot springs for the captain's baths, and declaring war on uninhabited continents to bother with trying to discover fire, invent the wheel, or solve pressing issues.