 In the Dark Ages, after the fall of the Roman Empire, the weak Britain is divided in several clans, while the powerful Ireland, untouched by Romans, dominates and spoils the British tribes. The fair and noble British leader Marke meets with the other chiefs trying to unite their country, but they are attacked and slaughtered by the Irish army leaded by Morholt. Marke looses one hand protecting the young Tristan, who had just lost his parents, and he raises the boy as if he were of his blood. Years later, after another attack of the Irish forces, Tristan rescues his people that were captured to serve as slaves and kills the mean Morholt, for whom the beautiful Irish princess Isolde was promised to get married. Tristan is poisoned by the sword of Morholt, declared dead by his mates, and is put on a boat for the funeral services. Isolde finds the boat with Tristan in an Irish beach with her maid-servant Bragnae, she saves him and along the days they fall in love for each other. When Tristan returns to Britain, Isolde lies about her name. Her father, King Donnchadh, together with the traitor Wictred, decides to promote a joust, to divide the British and make Wictred king, promising the hand of Isolde to the winner, but Tristan wins the tournament. Without knowing that Isolde is his love, Tristan offers her to Marke, to promote the union of Britain. When he sees who Isolde is, he has to decide between his friendship and loyalty to Marke and his love for Isolde.