The full title of Tim Harford's book is "The Undercover Economist: Exposing Why the Rich Are Rich, the Poor Are Poor - and Why You Can Never Buy a Decent Used Car!" There is a new revised and expanded 2012 version of this book out now. The original version was published in 2005.
It is a wonderfully clear book, quite readable for those without a background in economics, and it makes clear why many things in the economy work as they do. Political economic policy is often based on a fantasy world divorced from the real world we all live in, which is why political solutions so often fail to achieve their stated objectives (not to mention that their stated objectives are often not the real objectives of those who propose them!). For anyone trying to figure out what the nation ought to be doing right now, and trying to evaluate the proposals of both parties, this book is a good starting point