The Hitchhiker's Guide to the Galaxy by Douglas Adams
Arthur Dent is a guy just trying to get by in life. Then aliens show up and blow up the earth. Arthur narrowly escapes by hitching a ride on an alien spaceship with the help of his friend, Ford Perfect, an alien who has been posing for the past fifteen years on earth as an out-of-work actor, but is in fact a researcher for the manual, The Hitchhiker's Guide to the Galaxy.
This is one of those books that I didn't love, but I didn't completely hate it either, which surprises me, since I'm usually super into really geeky stuff like this. I really enjoyed the dry, British humor and the off-the-wall scenarios, but the story itself seemed to stay at the same, slow pace throughout the entire book. It just didn't hold my attention very well.
I give it a C+.
If you liked this one, The Restaurant at the End of the Universe is the next book in this series. Though honestly, I'm really not in any hurry to read it...
On the plus side, the movie version has Martin Freeman (AKA John Watson in Sherlock and Bilbo Baggins in The Hobbit franchise) in it. Might be worth watching just for him!