Over the course of ten days and 435 miles, an unshakable bond forms between Michael Light (Mark Wahlberg), a professional mountain endurance racer, and a stray dog named Arthur.
Based on an incredible true story, King Arthur is the story of Light, desperate for one last chance to win, as he convinces a sponsor to back him and a team of athletes (Simu Liu, Nathalie Emmanuel and Ali Suliman) for the World Championship of Adventure Racing in the Dominican Republic. As the team is pushed to the extreme limits of endurance, Arthur redefines what victory, loyalty and friendship truly mean.