This is a new edition of Paul Davies' very highly regarded text on high-energy particle physics aimed at the scientifically educated general reader. Since the appearance of the first edition in 1979 there have been many major developments in the field, and the author has taken this opportunity to bring the text completely up to date. Paul Davies includes details of one of the most significant of these developments, the experimental discovery in 1983 of the W and Z intermediate vector bosons, and discusses the implications for the eventual unification of the four forces of nature. In addition to this, the discovery of the top and bottom quarks, the details and predictions of modern grand unified theories (GUTs), and the application of the results of high-energy physics to studies of the very early universe are all included.