This book focuses on the five biggest one day races in cycling. These are in order of the book - Liege - Bastogne - Liege, Paris-Roubaix, Tour of Lombardy, Milan - Sanremo and Tour of Flanders. In cycling hierarchy, it goes basically the 3 grand tours then the 5 monuments (though it also depends on the riders) and then the rest really depends on where the riders are from on a seasons objectives. Of course other races are briefly mentioned but in context of the riders (Tou de France is in the index 28 times, Giro D'Italia 15 times and Vuelta isn't mentioned in the index.
Peter Cossins (former editor of ProCycling magazine) has done a really good jobs, he has worked to a structured plan on laying our. Each race gets four chapters, the first chapter tends to be pre World War I with some really good detail on the establishment of each race, the second chapter being the inter war period, the third chapters covering usually the 50s and 60s up to the 70s and the fourth chapter more recent times. Cossins has a fine eye for a good anecdote. One of which is that there is a story on the first running of Paris-Roubaix being that a catholic priest was unhappy with the race being ran on Easter Sunday, the race directeur arranged that an early morning mass so riders could attend mass. Cossins adds a further sentence to this story as a spoiler to it.
This was a really fascinating book, well researched with plenty of good sources in the bilbliography (2 of which I have read also being John Foot's excellent book on Italian Cycling Pedalare Pedalare and Laurent Fignon's autobiography. Though also in it is very knowledgeable cycling historian Les Woodland and other well known cycling writers like Daniel Friebe and William Fotheringham)
It isn't the full picture, some editions of the races are only briefly mentioned, others barely mentioned but in a book 370 pages long on 5 races, each race is worthy of it's own book (indeed looking at the bibliography, there has been several for many races :D) but this a really good read