A quick plot summary:

- The ultimate computer is constructed.
- It is told to answer the ultimate question - you know, the question of life, the universe, everything.
- It computes for 10 million years, and returns the answer: 42.
- Programmers are chagrined that they don't know exactly what the question is.
- A bigger computer is built to find out what the question is.
- It is blown up moments before completing its calculation.
- The book begins.