At the start of the 1998 major league baseball season, St. Louis Cardinals first baseman Mark McGwire hit a home run. In the games that followed, he did it again. And again. And again. And again. By the end of the season, in late September, he had done the hardest thing in baseball an earth-shattering seventy times. He didn't just break the decades-old single-season home-run record set by Roger Maris in 1961-he shattered it. And by doing so, he not only set a new benchmark for players to strive for, but also reminded people that baseball is fun, a game to be enjoyed, with heroes who play for...