This non-fiction book is an excellent entry into the study of logic, being both thought-provoking and fun. It contains some classic logic puzzles (like Zeno's paradox, which "proves" it is not possible to walk across a room) as well as the explanations needed to appreciate them. What's more, it's written in a highly readable style that makes a complex subject easier to grasp.
It's too bad that this book is out of print. However, members of a certain GoodReads group can find a copy on the classroom shelves of their moderator.