It's 2012, and for athletes from many countries—Kenya and Ethiopia among them—lifelong Olympic dreams are riding on the upcoming spring marathons. Will I run well enough to be chosen for the team? Will other athletes run faster and knock me out of my provisional spot? Which marathon gives me the best chance to show what I can do? And what exactly are the selection criteria, anyway? Not in the United States, one of the few countries in the world to select its Olympic track and field team via a strict Olympic Trials system: One day, one race, top three.