Watch VoirFilms. The legendary Dragon’s Back Race follows the mountainous spine of Wales from north to south. This incredible 5-day journey is 315 kilometres long with 15,500 metres of ascent across wild, trackless, remote and mountainous terrain. It is the toughest 5-day mountain race in the world. This film focuses on the highs and lows of five participants as they set out to conquer The Dragon. Each of them has a unique and emotional story to tell of their battle against the enormous physical and mental challenges of the race.