123Movies. Muay Thai. The world’s favorite martial art and the most dangerous sport. ‘5th Round’ follows the story of four boxers at different stages of their life. What they all have in common is that that their whole lives have been dedicated to Muay Thai. They can fight for their area, but they can’t choose their destiny. Born into poverty, boxing is their only means of earning a living, and if they are to find a better life, they must fight right though to the very last round.