For years, it's been one of the biggest questions in sport. Did Lance Armstrong - the seven time winner of cycling's greatest race, the Tour de France - dope? Is the man who beat cancer to become one of the greatest sporting figures ever - a cheat? Armstrong has denied wrongdoing. But now a former teammate and roommate of Armstrong's, Tyler Hamilton, has produced the most detailed and wounding set of allegations yet. Is Hamilton self-serving and greedy, as Armstrong insists? Or a shaft of light on a sport that's been mired in murk?