ARTHUR DENT Wakes up to the confused sound of Machines whirring around his house, threatening to take it down. He defiantly stays there until a friend, FORD PREFECT, informs him that the earth is about to explode.
FORD and ARTHUR manage to escape onto the VOGON ship and watch the world explode behind them. ARTHUR begins to panic until he realizes that he has more to panic about when the VOGONS throw them off the ship.
Our Heroes are picked up by a ship's improbability drive. The crew of this ship is made of MARVIN, a maniacally depressed robot; ZAPHOD BEETLEBROX, the zany president of the galaxy; and TRILLIAN, who really doesn't get as much character development as she deserves. Soon after FORD and ARTHUR get settled, the crew finds the mythical planet of Magrathrea, where they almost get shot trying to land.
Don't talk to ME about life
Once they land in Magraethrea, they immediately split up. ARTHUR gets found by SLARTIBARTFAST, who takes him to the insides of the planet while explaining bits of the past. He explains his lifestyle (He's a planet designer), he explains how mice have been experimenting on humans, and that the earth was just a computer calculating the question to which the answer is 42.
There is a flashback scene in which the computer is asked the meaning of life. 7 million years later, the computer reveals that the question was too vague, and that the answer was 42. The philosophers ask the computer what the question was, and it was about to come up with an answer when the VOGONS blew it up. Our heroes are back to the present, where they meet back up in a design studio in magrathrea.
In the design studio, our heroes learn that the Magrathreans were making a second version of the Earth for the mice. That was until the mice took notice of ARTHUR, whose brain could be used to make a copy of the earth, and they offered to buy his brain. He refused, shocked, and the mice began to fight the heroes. They somehow win and rush to the Heart of Gold, where they blast off and make plans to go to the restaurant at the end of the universe.