Part One (Continental Celts) deals with language, early bronze age Europe, Celtic migrations, Celts in Anatolia Italy and Iberia, trade routes, religion, the Roman conquest of Gaul and the kingdom of Brittany, among other topics. This section includes a diagram of the development of the Celtic language group.

Part Two discusses inter alia: prehistoric Celtic Britain and Ireland, the Roman conquest of Britain, the Picts and the Scots, King Arthur and the golden ages of Wales and Ireland.

Part Three investigates the Celtic Diaspora to places like Canada, the USA, Australia and South Africa, the Celtic languages today, the Celtic countries and the Celtic League which includes Ireland, Scotland, Wales, the Isle of Man, Cornwall and Brittany.

Of the surviving languages, Welsh has the greatest number of speakers, followed by Breton. Scottish Gaelic still survives in the Outer Hebrides and Irish is still spoken by small numbers in western parts of Eire. Manx and Cornish are "hobby" languages with less than 100 speakers each.

The book concludes with a list of further reading and an index. The text is enhanced with more than 200 illustrations of which 180 are in full colour and 54 beautiful maps. It is an extensive reference work filled with fascinating facts and illuminating history.