<DIV>The great myth of horse racing is that the game is the regal and royal Sport of Kings. It isn't. Not by a long shot.<p> Anyone who doubts this need look no further than Suffolk Downs, a once-proud racecourse graced in its glory years by boisterous throngs and champions such as Seabiscuit. Now the blue-collar East Boston track is one of many that have fallen on hard times. These days "Sufferin' Downs" is where grizzled Thoroughbreds come to end their careers, hopeful young jockeys aspire against daunting odds to begin them, and diehard fans cheer, curse and gamble on the entire fascinating spectacle. These bit players are not just cogs of a single, struggling horse track. They are the unseen supporting cast for a $15 billion betting industry.<p> In fifteen years as a racing reporter and press box personality, T.D. Thornton gained access to remote corners of racetrack life off limits to the general public. He got to know the raucously Runyonesque characters and the quirky personalities of the horses; he learned the tricks of the trade from trainers, owners, and jockeys; he witnessed the tragedies and small triumphs of racing lives lived below the radar. One recent season, he finally decided to write it all down.<p> <i>Not by a Long Shot</i> is a deeply textured portrait of an industry where even the best in the business lose 75 percent of the time.</div>