A new superstar appeared on the American sports landscape in the spring of 2006. Barbaro, a three-year-old racehorse, won the Kentucky Derby by the largest margin of victory in sixty years, stirring talk of a possible Triple Crown. But in the opening yards of the Preakness Stakes two weeks later, the magnificent animal suffered a catastrophic leg injury that ended his un-defeated career and left him fighting for his life.

One of the world's top jockeys, Edgar Prado rode Barbaro to glory and then stood beside him for months as the horse valiantly struggled to survive. My Guy...