Book excerpt: Every horse endurance ride has its challenges and difficulties, but the Tevis Cup has 100 miles of it. It's extreme, challenging, relentless, frantic, exhilarating, heart-breaking, exhausting, exasperating, beautiful, treacherous, insane, exciting. Merri Melde's dramatic story of her unplanned and unforeseen attempt at the Tevis Cup, the world's toughest 100 mile endurance ride, will put you in the saddle, gripping the reins, racing the clock to cross the finish line in the 24 hour time limit, on a beautiful, gallant gray horse.