Nick Lane's: Life Ascending: The ten great inventions of Evolution.
http://www.amazon.com/Life-Ascending-Great-Inventions-Evolution/dp/0393338665I think I can say this is probably the best book I've read on the workings of life, particularly the first chapter on the origin of life was simply amazingly well written. The previous book I read on a similar subject was
Into the Cool: Energy flows, thermodynamics and life. I though
that was a good book.
It's not a book about how evolution works (and as such is not a book about the evidence for evolution, so it's not a book for your fundamentalist creationist friend), it's a book about how living cells function, how they extract their energy from their surroundings, when they learned to do it - and what evolution has produced of marvelous processes inside them, including the origin of life itself. Which, incidentally, is also the theory on life's origin I happen to find most plausible and Nick Lane goes through all the reasons why.