Fermat's Enigma, by Simon Singh

Fantastic walkthrough the history of Mathematics as the author presents the work of Andrew Wiles, the man who was able to prove Fermat's Last Theorem. At no point this is a boring book, not even when discussing details in higher level math. Singh's unparalleled talents allow him to impart excitement and bewilderment for science and its history onto the most uninitiated reader. The book is an excellent appetizer for number theory.