The Tertiary Phase
Fit the Thirteenth
Arthur wakes up in a cave on pre-historic Earth, as Ford returns from a four-year absence. Ford brings news that he has detected disturbances in the "space-time wash", and that they might be able to escape. The disturbance turns out to be a Chesterfield sofa, which materialises in a field. They chase the sofa as it moves off, and manage to jump aboard before it disappears. Zaphod and Trillian are aboard the Heart of Gold. Zaphod is extremely hungover, and upset that Trillian is dismissing the events of The Secondary Phase as a "psychotic episode". Utterly frustrated, Trillian tells the computer to "transport me the hell out of Zaphod Beeblebrox's life." Meanwhile, Marvin is stuck in a swamp on Squornshellous Zeta, talking to the native inhabitants: mattresses.
Fit the Fourteenth
Transported by the sofa, Arthur and Ford arrive at Lord's Cricket Ground during the final Test Match of the Ashes. When a ball lands in Arthur's bag, he decides to keep it. He discovers from a newspaper that it is the day before the Earth was demolished. Ford discovers a spaceship, hidden by a "Somebody Else's Problem field". This spaceship belongs to Slartibartfast, who walks on to the pitch as the game ends, demanding to be given the Ashes. Another spaceship arrives, and eleven white robots emerged, dressed like cricketers. They attack, take the Ashes and leave. Ford and Arthur set out in pursuit with Slartibartfast on his ship. Meanwhile, Marvin is still talking to mattresses. The white robots arrive, and remove his leg, returning shortly after for the rest of him.
Fit the Fifteenth
Slartibartfast explains to Ford and Arthur that the game of cricket on Earth is a "racial memory" of the Krikkit Wars. The Krikkit Men, a previously peaceful people, built their first spaceship in a year after a spaceship crashed on their planet. The planet and its sun had been previously obscured in a dust cloud that left the Krikket Men unaware of even the possibility of the existence of other planets. Once they discovered that the rest of the universe existed, they decided it must be annihilated. After the Krikkit Men attack on the universe, the planet Krikkit was sentenced to be locked in an envelope of Slow Time until the end of the universe. However, one Krikkit ship escaped, and now appears to be seeking the components of the key to the Wikkit Gate which could be used to unlock the envelope of Slow Time. On the Heart of Gold, Zaphod intercepts the white robots who appear on the bridge, they tell him that they want the "Golden Bail", the ship's Infinite Improbability Drive. They take it, shoot him, and leave. Having failed to recover the 'Wooden Pillar' (the Ashes), Slartibartfast plans to go to a party to locate the 'Silver Bail'. He, Ford and Arthur teleport from the ship, but Arthur does not materialise at the party with them. He appears in a gloomy room, with signs that tell him, "DO NOT BE ALARMED. BE VERY VERY FRIGHTENED, ARTHUR DENT".
Fit the Sixteenth
Arthur has been "diverted" by Agrajag, who claims that Arthur has killed hundreds of his previous incarnations - including the bowl of petunias that came into existence when Arthur activated the Infinite Improbability Drive in Fit the Third. When he discovers that one of these 'murders' has not yet taken place (an encounter on Stavromula Beta), he realises that he has captured Arthur too soon, but decides to try to kill him anyway. Arthur and Agrajag struggle, and Agrajag dies. Arthur escapes down a passageway in the mountain, and notices that he has somehow ended up with the wrong bag - he now has one he lost on Earth many years ago. He trips, and discovers that he can fly. While flying, he is hit by the party that Ford and Slartibartfast are trying to get into. Once inside the party, they see Trillian. Slartibartfast discovers that the Silver Bail has been made into an award for the Most Gratuitous Use Of The Word Fuck In A Serious Screenplay. But before he can get hold of it, the Krikkit robots appear, massacre the party-goers and take the Silver Bail. Trillian joins Ford, Arthur and Slartibartfast - who realises that the Krikkit Men now have all the components of the Key, and that they must try to stop them at the Wikkit Gate itself.
Fit the Seventeenth
Arthur, Ford, Trillian and Slartibartfast arrive at the asteroid that forms the Wikkit Gate, but are too late to prevent the robots from opening the gate. The robots then destroy the lock and key, and Arthur recovers the Golden Bail and the Ashes. Zaphod, who had been brought by the Krikkit robots on their ship, takes the Golden Bail back to the Heart of Gold. Arthur, Ford, Trillian and Slartibartfast land on Krikkit, passing hundreds of buildings and warships floating above the planet. They are apprehended by some Krikkit Men, who appear to be concerned about the plan to destroy the universe. One, terribly upset, tells Trillian that they have a bomb capable of destroying everything that exists. Trillian asks him to take her to his leader in the sky. Meanwhile, Zaphod has discovered the original starship that crashed on Krikkit, and realised that it is a fake. He also finds out that the Krikkit robots have become depressed.
Fit the Eighteenth
Zaphod discovers that Marvin has been plugged into the Krikkit mainframe and is being used as its central computer; this has caused the robots to become depressed, and has also stopped them killing Zaphod. Trillian tells the elders of Krikkit that their history has been manipulated by someone who wants the universe to be destroyed. This is Hactar, a computer which had once been asked to design and build an Ultimate Weapon, but which had instead created a dud weapon, for which it was destroyed. Hactar explains that his matrix had not be completely disintegrated, and he had come to regret his decision not to create the weapon. He had formed the dustcloud that isolated Krikkit, and created the spacecraft that had precipitated them into war. His final words before the Heart of Gold blows the dustcloud apart are, "I have fulfilled my function..." The Heart of Gold has also picked up a man named Prax, who was given a massive overdose of a truth drug, and told to tell 'the whole truth'. Arthur asks him if he knows the Ultimate Question, but he explains the knowledge of the Question and the Answer are mutually exclusive. However, he mentions that he knows that location of God's Last Message to his Creation, but dies before revealing it. Arthur and co return the Ashes to Lord's Cricket Ground. Arthur sees a batsman at the wicket, and realising that he still has the ball which he caught on his previous visit, is tempted to bowl. Ford realises that the batsman is a Krikkit robot, and that the ball is probably Hactar's bomb. Fortunately, Arthur bowls wide, and Ford catches the ball.
