Tristan & Isolde's story of star-crossed lovers immediately suggests Romeo & Juliet but perhaps even more than that, it is evocative of the Arthurian legend of Camelot.
It is the 7th century, and the Roman Empire has fallen. A fragmented Britain is divided into eight tribes whose unwillingness to unite weakens their defence against a unified Ireland. Aware of this, the Irish king, Donnchadh (David Patrick OHara) regularly sends his forces to England to quell any signs of rebellion and unification.
The most likely man to be king of a unified Britain is Lord Marke (Rufus Sewell), whose best warrior is Tristan (James Franco) - adopted by Marke when Tristans parents were killed during one of the Irish assaults. After yet another of these raids, Tristan leads the men in a retaliatory attack during which he is presumably killed. His funeral pyre is sent out to sea and later washes up on the Irish shore where he is discovered by King Donnchadhs daughter, Isolde (Sophia Myles) and her maid, Bragnae (Bronagh Gallagher). Tristan is still alive and Isolde nurses him back to health. The two become lovers, but Isolde does not reveal her true identity to Tristan whom she helps to escape when her father becomes aware of his presence in the country. Tristan returns to England and is reunited with Lord Marke who welcomes him back from the dead.
Still determined to maintain instability in England, Donnchadh offers Isolde as a bride in a tournament in which the best fighters from the various English tribes will compete. Tristan wins the competition but - unaware that he has been fighting for the woman he loves - he has entered it in order to win Isolde for Lord Marke.
Marke and Isolde marry, and Tristan desperately tries not to betray the beloved man who treats him like a son. Inevitably, however, he and Isolde become lovers again. Their illicit passion makes them pawns in Donnchadhs own schemes to destroy Britain, aided by the treachery and ambition of the ruler of one of the English tribes. The discovery of Tristan and Isoldes secret affair has monumental consequences that could forever destroy Lord Markes hopes for a unified England.
Played out in spectacular settings, Tristan & Isolde - a legend that has even inspired a Wagnerian opera - tells of love, war, passion, betrayal and ultimately, tragedy - all the elements of classic storytelling.