Blue Fall by B. B. Griffith
If you knew about The Tournament, you'd know why they want it kept secret. People don't like to hear that state-sponsored war games are going on under their noses, in their cities, and on their streets. The world isn't ready to know that the most powerful among us can shape the future by wagering on these fights. People wouldn't understand if they learned that teams in The Tournament have the freedom to do almost anything, anywhere, to win.
The Tournament was supposed to be the perfect game, and the perfect secret. Frank Youngsmith, a hapless insurance agent, was supposed to be a nobody, none the wiser. But sometimes things just don't work out like they're supposed to. When Frank stumbles into the dark world of The Tournament when the game is on, it's up to him to expose the secret...or die trying.