In the first act Isolda and Tristan enjoy their love only for a few minutes; the world, daylight, breaks in and separates them. In the second they revel in it for hours; the world, daylight, again separates them. In the last the world again breaks in; but Tristan has already found his refuge in death, and Isolda, obedient to her promise, follows him, and they are joined, safe from the annoyances of the "phantoms of the day," in "the impregnable fortress," the grave. The action, as in the preceding portions of the drama, is of the simplest. On his bed of pain and sorrow Tristan lies wounded and unconscious. Kurvenal has got him away from Mark's court in Cornwall to his own castle in Brittany; and now he has been brought out into the castle yard for coolness and air. It is hot, sultry, close; the sea in the distance seems to burn; the castle is dilapidated and overgrown with weeds. Kurvenal watches by his master; from outside the saddest melody ever conceived is heard on a shepherd's pipe. Presently the shepherd looks over the wall and asks how the master fares, does he still sleep? If he awakes it will only be to die, replies Kurvenal; unless the lady leech (Isolda) comes there is no hope. A moment after Tristan comes out of his coma, wanders in his mind a little, but at last understands where he is and that Isolda will come. At that news he works himself into a condition of unbounded excitement, fancies he sees the ship bringing Isolda, but at the sound of that sad, droning pipe melody, and when Kurvenal tells him it is a signal that no ship is yet in sight, he lapses into unconsciousness again. Then he wakes up, goes over the whole history of his love for Isolda, and faints once more; once more he half awakes and as in a dream sees the ship decked with flowers speeding over the summer sea. Suddenly the shepherd strikes in with a lively tune: "Isolda is at hand," cries Kurvenal. "Hasten to bring her," shouts Tristan, and Kurvenal does so. Tristan, left to himself, goes mad for sheer joy, staggers off his couch, tears his bandages off so that his wound bleeds afresh, and Isolda rushes in just in time to catch him in her arms, where he dies murmuring "Isolda." She laments over his body and sinks down beside it. Another alarm is given; Kurvenal barricades the gate; Mark, Melot and the rest break it down, and there is a terrible hand-to-hand fight; Kurvenal is run through with a spear, and creeps to his master's side, to die, groping for his hand. Brangaena enters, and she and Mark try to explain how she has told the whole story of the potion to Mark; how Mark has come, too late, to unite the lovers. Isolda does not listen; presently she rises to sing the matchless death-song; she sees Tristan before her, smiling, transfigured, his love envelopes her as in billows; she is his now, at last, for aye; and, exhausted, she again sinks down beside Tristan, and dies.