The book is, The World Of The Druids by Miranda J. Green.
The World of the Druids is one of those books I checked out from the library and decided that I needed to own it. In fact I believe I read it 5 times before recently purchasing it. It is a very good overview of the Celts, their Druids, and their gods, religion, and society. Included are also sections on modern day druidism and even neo-paganism. The imagery, tables, and artwork add to the appeal of the book.
The World of the Druids is a great book for those interested in the Druids and of the Celts and who would like solid information devoid of the romantic interpretation first put forward in the 18th century. Don't get me wrong, the book does indeed touch on the romantic interpretations of the Druids yet separates such views to place them in context.
The book definitely clears-up much misinformation on the Druids, their belief structures, and forms of worship. Green is very careful to point out what we know and what we don't know concerning the Celts and their religion.
On a scale of 1 to 10, with 1 being the lowest and 10 being the highest, I give this book a 10. If you are interested in the Druids, or the Celts, then this is definitely a book you are likely to want in your collection.