Life, the Universe and Everything is the third book in Douglas 
Adam's Hitchhiker's guide to the Galaxy trilogy. 
    This book starts off with Arthur Dent waking up in a cave on 
prehistoric Earth and yelling in horror when he realizes where he is. 
You may be wondering why he is there and how he got there, the answer 
is not simple and so to find out your going to have to read the 
prequels:  The Hitchhiker's guide to the Galaxy and The restaurant at 
the end of the Universe.  I will, however, tell you that in this book 
there is an immortal being whose sole purpose is to insult the entire 
universe, in other words, to insult everyone, individually in it. 
This is just an example of Douglas Adams outrageous plots. 
    This book is an amazing combination of both science fiction and 
comedy.  In my experience I have never seen anything like this and I 
must say it is very good.  If you enjoy reading humorous science 
fiction novels, I recommend The Hitchhikers series, starting with The 
Hitchhiker's guide to the Galaxy and ending with So long and thanks 
for all the Fish.