The Book: Peter Jones Arthur Dent: Simon Jones Ford Prefect/Ventilation System: Geoffrey McGivern Zaphod Beeblebrox: Mark-Wing Davey Vogon Captain: Bill Wallis Marvin the Paranoid Android/Vogon Guard/Gag Halfrunt: Stephen Moore Eddie the Computer/Vogon Guard/Vogon Computer: David Tate Nutrimat Machine: Leueen Willoughby Zaphod Beeblebrox IV: Richard Goolden Announcer (uncredited): John Marsh One of the singing robots (uncredited): Geoffrey Perkins Another of the singing robots (uncredited): Paddy Kingsland
The episode opens with Ford and Arthur discussing Zaphod's sanity on board the Heart of Gold. Ford also starts correcting Arthur's grammar, forcing Arthur to refer to Earth in the past tense, as it had been demolished in Fit the First. Ford then begins to question the reason given for the demolition, stating "that was all done away with centuries ago. No one demolishes planets anymore." Ford has noticed another fleet of Vogon ships following the Heart of Gold at a distance of five light years for half an hour. He then calls for Marvin to bring Zaphod to the bridge.
Meanwhile, Prostetnic Vogon Jeltz confirms the identity of the ship and its occupants, then proceeds to wipe out half his crew in a fit of rage. After this massacre, he contacts Gag Halfrunt. Halfrunt is revealed not only to be Jeltz's psychiatrist (as well as Zaphod's), but also the psychiatrist who originally hired Jeltz to destroy first the Earth, then any survivors. Jeltz is asked to hold off on his final destruction of the Heart of Gold until Halfrunt can make an arrangement for fees still owed by Zaphod.
Halfrunt contacts Zaphod, who has since arrived on the Heart of Gold's bridge, but refuses to see the Vogon threat as anything more than a delusion of grandeur. Zaphod destroys the Heart of Gold's radio, then attempts to get the ship's computer to engage the Infinite Improbability Drive in order to get the Heart of Gold away from the Vogons. The computer states that this is not possible, as all its circuits have become busy with another task, and insists that the result will be something they can all "Share and Enjoy."
The Guide explains that "Share and Enjoy" is the motto of the Sirius Cybernetics Corporation Complaints Division. A song, sung by the company's robots, with voices a flattened fifth out of tune, is heard. Another product of SCC that never works, the Nutrimat, is introduced, as Arthur is attempting to get it to dispense tea. Arthur eventually converses with the Nutrimat, the floor and the ventilation system, trying to convince them that he wants tea, when Eddie the ship's computer is finally brought in, to work out "why the human prefers boiled leaves to everything we have to offer him...."
This is then revealed to be the problem preventing the computer from evading the Vogons. Zaphod decides to contact his great-grandfather, Zaphod Beeblebrox IV, through a seance. More background behind Zaphod's actual job and a conspiracy to discover the real ruler of the universe is revealed. As the episode ends, Eddie has been restored to normal function, and engages the IID, getting the ship out of firing range of the Vogons in the nick of time.