An affair between the second in line to Britain's throne (Franco) and the princess of the feuding Irish (Myles) spells doom for the young lovers.

[last lines]
Isolde: [reading] My face in thine eye, thine in mine appears, And true plain hearts do in the faces rest; Where can we find two better hemispheres Without sharp north, without declining west? Whatever dies, was not mix'd equally; If our two loves be one, or thou and I Love so alike that none can slacken, none can die.
Isolde: Why?
Tristan: There are other things to live for: duty, honor.
Isolde: But they are not life Tristan. They are the shells of life, and empty ones if in the end all they hold are days and days without love. Love is made by God. Ignore it and you suffer as you cannot imagine.
Tristan: Then I will no longer live without it.
Isolde: Yesterday at the market, I saw a couple holding hands... and I realized we'll never do that. Never anything like it. No picnics or unguarded smiles. No rings. Just... stolen moments that leave too quickly.
Tristan: [to Isolde] I live in torture thinking of these moments. Every look he gives you I get sicker and sicker. There's a burning in me, I feel on fire and a guilt I can't comidify. Does it make you happy to know that?
Isolde: Know that I love you Tristan. Wherever you go, whatever you see. I will always be with you.
[his last lines]
Tristan: You were right. I don't know if life is greater than death. But love was more than either.
Lord Marke: Do you find no comfort in your home, these stearn walls that you helped build?
Tristan: I find these walls a prison.
Lord Marke: Why?
Tristan: Everything I wanted seems meaningless.
Tristan: Come with me. Come with me!
Isolde: I can't!
Tristan: Why not? Please!
Isolde: Tristan, we both know this can't be, we've known it from the start. That doesn't mean it isn't true, it is, it just cannot be. I want to know that you're alive somewhere thinking of me from time to time. I want to know that there's more to this life and I can't know that if they kill you. Please! Go.
Tristan: [fleeing Ireland] Come with me.
Isolde: I can't.
Tristan: Why not?
Isolde: We both know this cannot be, Tristan. We knew it from the start. That doesn't mean it wasn't true, it is.
Tristan: I live in torture, thinking of these moments. With every look he gives you, I get sicker and sicker. There is a burning in me I feel on fire, and there's guilt I can't comidify. Does it make you happy to know that?
Isolde: The Roman Bridge, I can get to it without being seen, and I'd go there any time to be with you.
Lord Marke: What if she's a hag? Or what if she simply won't have me?
Edyth: She'll have you. You're the prize.
Isolde: How many have you loved before me?
Tristan: None.
Isolde: And after me?
Tristan: None.
Isolde: What do you think became of them?
Tristan: They were lives... just lived.
Isolde: You risked your life to give me to another man.
Tristan: You said your name was Bragnae. Why did you do that?
Isolde: Oh, what have I done? Stop this, please, Tristan, say something.
Tristan: I can't. I won you in my King's name.
Isolde: But I'm your's. You touched me and I you.
Tristan: It doesn't matter.
Isolde: It's the only thing that matters, Tristan. Leave with me, I'll go anywhere!
Young Isolde: Why did she die, Bragnae? Why?
Bragnae: It was an ill vapor that took her. A fever.
Young Isolde: No. It was her heart.
Melot: You have one more fight, Tristan. Take deep breaths.
Melot: [on Tristan] Behold your hero, Uncle.
Melot: [lying in the tunnel] A dozen Irish have blazed your way.
Tristan: Melot, I swear I did not lead them here.
Melot: No, I did.
Tristan: Why?
Melot: I thought someone believed in me.
Tristan: It will be undone.
Melot: I am for the worms, Tristan. Swear to me that you are true.
Tristan: As we were brothers.
Tristan: What's your name?
Isolde: Oh, I think it's better if we don't bother with names.
Tristan: How can I thank you if I don't have your name?
Isolde: You just did. If you insist, my name is Bragnae. I'm a lady in waiting at the court. My parents are dead. My mother is the source of the kindness you find so puzzling. My father would've left you where you fell.
Tristan: Tristan of Aragon.
Isolde: Well Tristan of Aragon, I'd guess about you too, but I think I've already seen everything.
[from trailer]
Isolde: I want to know that there's more to this life, and I can't know that if they kill you.
[she Kisses Tristan]
Tristan: [to Lord Marke] She is loyal to you. I am sure of it.
Isolde: And your parents?
Tristan: They also died when I was young.
Isolde: From what?
Tristan: Another different type of Irish kindness.
Lord Marke: [on the affair] How long?
Isolde: Since you thought he was dead. I found him wounded on a beach in Ireland. And I told him my name was Bragnae. So when he came to the tournament at Dunluce to win Doncadh's daughter he didnt realize it was me. All this time, my heart has been his. And I'm sorry. He tried, harder than you can possible imagine because he loves you.
Isolde: [on dreaming of things] ... a child.
Tristan: Will it be mine or his?
Isolde: I'd have no way of knowing, would I?
Isolde: Tristan, if we do this...
Tristan: For all time they will say it was our love, brought down a kingdom. Remember us.
[pushes the boat away]
[first lines]
Aragon: A year younger than I was for my first.
Young Tristan: When can I have a stag?
Aragon: A stag?
Young Tristan: Come on!
Aragon: Tell me again what you said last week...
Tristan: Your marriage will end a hundred years of bloodshed.
Isolde: [sobbing] My marriage to another man!
Lord Marke: [to Tristan] Is it possible a man blinded by love might not see treachery right in front of him?
Lord Marke: I came to apologize. I've been selfish, arrogantly thinking that perhaps I'd given enough in these past nine years to merit if not your love, then at least your respect. A home, a kingdom, your very life. Why was it not enough? Tell me. TELL ME! Do you not know what you have done? Everything is destroyed! Everything! All because you did not have enough! 'She is loyal to you, I am sure of it.' You bloodsucker. What I could have been had I not stretched out this hand to save your wretched life, how I curse that day. How I curse it. Well, insult me with your defense.
[from trailer]
Tristan: What's your name?
Isolde: Oh, I think it's better if we don't bother with names.
Bragnae: I've not been naked with a man for 15 years.
Lord Marke: Do you know what you have done?
Lord Marke: If we lose we could end up following Wictred. I'd need an infallible champion.
Tristan: Me.
Lord Marke: [chuckles] You are not yet healed.
Tristan: Then this trip will be my tonic.
[first lines]
Title Card: Britain. The Dark Ages. / The Roman Empire has fallen / The land lies in ruins, divided among feuding tribes. / To the west, Ireland has flourished - untouched by the Romans, protected by the sea. / Led by their powerful and righteous king, the Irish have subdued the Britons... / Knowing that if Ireland is to prosper, the tribes must never be allowed to unite.
Kurseval: What do we do now, My Lord?
Lord Marke: Rebuild.
Tristan: You're promised?
Isolde: Yes.
Tristan: What's he like?
Isolde: Dark. Tall. Nearly twice your size. An absolute gentleman.
Isolde: Why does loving you feel so wrong?
Lord Marke: Did I love him like a son? Or did I misuse him for my own purposes?
Isolde: I'm yours!
King Donnchadh: No, Tristan has won you on behalf of Lorde Marke.
[Tristan looks up at Isolde surprised]
Tristan: I make it my habit to follow no one.
Wictred: Except Marke.
Tristan: Marke delivered me from that palace when I was a boy. You ran. So you can understand, when I think of kings, I think of him. And when I think of cowards...
[is cut off by Marke]
Tristan: Isolde, we can't.
Isolde: It's like asking me to stop breathing.
Tristan: What's this about a tournament?
Lord Marke: The king has offered his daughter to whichever man wins.
Tristan: Let me go and win you a wife.
[hold Wictred's head and shows it to the entire Irish army]
Tristan: Behold! The Head of a Traitor!
Tristan: I am delivered.
Isolde: [reading] My face in thine eye, thine in mine appears, And true plain hearts do in the faces rest; Where can we find two better hemispheres Without sharp north, without declining west? Whatever dies, was not mix'd equally; If our two loves be one, or thou and I Love so alike that none can slacken, none can die.
Isolde: If things were different, if we lived in a place without duty, would you be with me?
Tristan: That place does not exist.
Isolde: [sobs] I'll pretend it's you.
Melot: Build my boat.
Lord Marke: I want him to grow old in a land where all of us are at peace