The date was October 3, 1951: the culmination of the most improbable comeback in the history of baseball. The New York Giants were trailing the Brooklyn Dodgers by 13 1/2 games in early August. But on this fall day at the Polo Grounds an improbable hero would accomplish the unthinkable: hitting a home run to give the Giants the National League pennant and a trip to the World Series.

In The Echoing Green - The Untold Story of Bobby Thomson, Ralph Branca, and The Shot Heard Round The World (Vintage), Wall Street Journal reporter Joshua Prager expands on a story he first reported in 2001: baseball's most famous home run may have been aided by a telescope employed by the New York Giants to steal signs from the Brooklyn Dodgers.

Mr. Prager admits in the afterword to the book that digging into such a beloved baseball memory had its pitfalls. By investigating this story he was running the risk of tainting a national treasure, for Thomson's home run had a far greater impact on the nation as a whole than any other event, sporting or otherwise, had up to that point in history. As a result, he took great pains to make sure he had the details surrounding the event just right as his appendix of sources shows.

But those details are both the book's biggest strength and weakness. At times the wealth of information Mr. Prager uncovers is fascinating. At other times, particularly early in the book, the exhaustive details tend to be a distraction and at times cause lengthy detours from the overall narrative.

Still, Mr. Prager manages to capture the essence of the actual event and, more importantly, the impact that Thomson's home run had on both men and society as a whole. The strongest part of the book is what happened after the home run and, unfortunately, that's the part that doesn't get enough attention.

Mr. Prager also is assisted by cooperation from both Mr. Branca and Mr. Thomson. Their recollections provide a keen insight into not only the memorable game but the lasting impact that one pitch had on both men. It's fair to say the first thing that will be said about either one of them when their obituary is written will be their involvement in the one playoff game. But more importantly, we see how both men have been able to make peace with each other and accept what happened on that afternoon in '51.

As baseball books go, this is a solid effort. Not exactly a home run, but still a solid triple. Mr. Prager is to be applauded for taking on one of the most sacred events in baseball. His detailed account does not diminish the accomplishment of Thomson or the Giants. In reality, it simply gives baseball fans more to talk about. That's a good thing.