A gripping tale of two young lovers whose forbidden love crosses the boundaries of rival kingdoms and marital commitment. At the film's commencement, Britain is at war with Ireland, and the English lords and barons are seeking to form an alliance to overturn the ruthless Irish king, Donnchadh. However, on the night they are to sign treaties to unite their kingdom, the Irish penetrate the Castle Tantallion, slaughtering all but a few of the English. Among these is young Tristan of Eragon, whose life is saved by Lord Marke, Britain's only promising leader remaining.
As Tristan enters his young adult years, having been raised and nurtured by Lord Marke, he uses his sharpened knowledge and cunning battle skills to fight bravely against the Irish when they cross into the Land of Cornwall. Though he defeats their strongest warrior, Morholt, he suffers a fatal strike of poison, and is presumed dead with his fellow martyrs. The triumphant English soldiers return with a bittersweet victory, and inform Lord Marke of the grievous loss.
However, when Tristan's burial vessel washes ashore the Irish coast, he is found by the beautiful Princess Isolde, daughter of King Donnchadh, who discovers that he is indeed alive. Distraught by a betrothal to an undesirable suitor in her father's army, and desperate for a life of true meaning, she risks her life to save Tristan. With the assistance of her disapproving maid, Bragnae, she spends her days and nights solely caring for Tristan's wounds, and sharing her heart's wishes - to have love, for it is greater than life.
Although Isolde conceals her true identity as the princess of Ireland, that doesn't stop their young attraction from blossoming into a deep love for each other. Nevertheless, the remaining defeated Irish soldiers return to the coast of Ireland, and Tristan is forced to leave before he is discovered by the king. With the hope that their love will exist even if apart, Tristan and Isolde bid farewell, and he returns back to the Castle D'or, knowing his heart will never be the same.
With the untimely death of his prize warrior, and desperate for a means to retaliate to the English, King Donnchadh decides to hold a tournament - a battle between the barons for the prize of his daughter, Isolde. The victor will insure a truce between the nations, in which time King Donnchadh plans to replenish his forces and devise a final attack.
When Lord Marke hears of the plans, he fears the barons he hopes to unite as a strong kingdom of England will fall for this devious plan, including the skeptical Wictred, whose cowardly manner is reminiscent of a would-be traitor. Tristan, seeking to rid his heart of depression, and eager to please Lord Marke, begs to fight in his place and win him a bride - a queen to bring the warring nations to unity and peace.
Once granted the journey to Ireland, Tristan arrives and fights courageously, even defeating his final opponent Wictred only to discover that the prize he is to give to Lord Marke is his dear love, Isolde. Heartbroken and torn by their impasse, Isolde begs Tristan for escape, so that they can be together. Yet Tristan is loyal to his promise to the king and desire for an end to the years of bloodshed, and vows to live with the pain and sorrow of seeing Isolde wed Lord Marke.
Nevertheless, time bears a heavy strain on the young lovers and their true emotions eventually surface. Unable to live without true love, and bound by the unfortunate circumstances, they see each other in secret, stealing moments away to be together in any way they can. However their secret is not safe for long, as the scheming Wictred discovers their affair and quickly arranges with King Donnchadh to unveil their love at the coronation ceremony and then invade Cornwall.
Once discovered, Lord Marke is overwhelmed with the blatant betrayal and deceit in his own beloved Tristan, loved like a son, and his dear Isolde, whom he has fallen deeply for. After hearing the truth of their love's beginning in Ireland and struggle until the present, he graciously accepts the truth and gives them their freedom. Seizing Marke's moment of weakness, Lord Wictred and King Donnchadh join forces to penetrate the castle, along with the distrusting members of Marke's seemingly doomed treaty.
Shocked and awed by the King's nobility, Tristan is unable to leave the English with Isolde, and sends her off to return and fight bravely in Lord Marke's favor. His undying loyalty plays the key role in overturning the Irish' futile attempts to invade the Castle D'Or. While he succeeds in killing Wictred, and unveiling the traitors of England, he suffers a fatal wound. Isolde rushes to be by his side at the bitter conclusion of the battle, where Tristan finally acknowledges their love to be truly greater than life, and then dies. . .
A memorable story that draws you in further, envelops you in the estranged love that stretches beyond the sea that separates England and Ireland, and breaks your heart every time. It defines the feats that true love will go to - that it can go beyond life, that it is greater than death, that it is the epitome of happiness and sorrow... Tristan & Isolde.