The opening scene is in a forest, in an unknown land. It is autumn. Golaud, gray-bearded, stern, a giant in stature ("I am made of iron and blood," he says of himself), has been hunting a wild boar, and has been led astray. His dogs have left him to follow a false scent. He is about to retrace his steps, when he comes upon a young girl weeping by a spring. She is very beautiful, and very timid. She would flee, but Golaud reassures her. Her dress is that of a princess, though her garments have been torn by the briars. Golaud questions her. Her name, she says, is Mélisande; she was born "far away;" she has fled, and is lost; but she will not tell her age, or whence she came, or what injury has been done her, or who it is that has harmed or threatened her—"Every one! every one!" she says. Her golden crown has fallen into the water—"It is the crown he gave me," she cries; "it fell as I was weeping." Golaud would recover it for her, but she will have no more of it.... "I had rather die at once!" she protests. Golaud prevails upon her to go with him—the night is coming on, and she cannot remain alone in the forest. She refuses, at first, in terror, then reluctantly consents. "Where are you going?" she asks. "I do not know.... I, too, am lost," replies Golaud. They leave together.
The scene changes to a hall in the castle—the silent and forbidding castle near the sea, surrounded by deep forests, where Golaud, with his mother Geneviève and his little son Yniold (the child of his first wife, now dead), lives with his aged father, Arkël, king of Allemonde. Here, too, lives Golaud's young half-brother, Pelléas—for they are not sons of the same father. Half a year has passed, and it is spring. Geneviève reads to her father, the ancient Arkël, a letter sent by Golaud to Pelléas. After recounting the circumstances of his meeting with Mélisande, Golaud continues: "It is now six months since I married her, and I know as little of her past as on the day we met. Meanwhile, dear Pelléas, you whom I love more than a brother, ... make ready for our return. I know that my mother will gladly pardon me; but I dread the King, in spite of all his kindness. If, however, he will consent to receive her as if she were his own daughter, light a lamp at the summit of the tower overlooking the sea, upon the third night after you receive this letter. I shall be able to see it from our vessel. If I see no light, I shall pass on and shall return no more." They decide to receive Golaud and his child-bride, although the marriage has prevented a union which, for political reasons, Arkël had arranged for his grandson.
Again the scene changes. Mélisande and Geneviève are walking together in the gardens, and they are joined by Pelléas. "We shall have a storm to-night," he says, "yet it is so calm now.... One might embark unwittingly and come back no more." They watch the departure of a great ship that is leaving the port, the ship that brought Golaud and his young wife. "Why does she sail to-night?... She may be wrecked," says Mélisande.... "The night comes quickly," observes Pelléas. A silence falls between them. "It is time to go in," says Geneviève. "Pelléas, show the way to Mélisande. I must go 'tend to little Yniold," and she leaves them alone. "Will you let me take your hand?" says Pelléas to Mélisande. Her hands are full of flowers, she responds. He will hold her arm, he says, for the road is steep. He tells her that he has had a letter from his dying friend Marcellus, summoning him to his bedside, and that he may perhaps go away on the morrow. "Oh! why do you go away?" says Mélisande.
ACT II
The second act begins at an old and abandoned fountain in the park—the "Fountain of the Blind," so called because it once possessed miraculous healing powers. Pelléas and Mélisande enter together. It is a stifling day, and they seek the cool tranquillity of the fountain and the shadow of the overarching trees—"One can hear the water sleep," says Pelléas. Their talk is dangerously intimate. Mélisande dips her hand in the cool water, and plays with her wedding-ring as she lies stretched along the edge of the marble basin. She throws the ring in the air and it falls into the deep water. Mélisande displays agitation: "What shall we say if Golaud asks where it is?" "The truth, the truth," replies Pelléas.
The scene changes to an apartment in the castle. Golaud lies upon a bed, with Mélisande bending over him. He has been wounded while hunting. Mélisande is compassionate, perhaps remorseful. She too, she confesses, is ill, unhappy, though she will not tell Golaud what it is that ails her. Her husband discovers the absence of her wedding-ring, and harshly, suspiciously, asks where it is. Mélisande, confused and terrified, dissembles, and answers that she must have lost it in a grotto by the seashore, when she went there in the morning to pick shells for little Yniold. She is sure it is there. Golaud bids her go at once and search for it. She fears to go alone, and he suggests that she ask Pelléas to accompany her.
The next scene discovers Mélisande with Pelléas in the grotto. They are deeply agitated. It is very dark, but Pelléas describes to her the look of the place, for, he tells her, she must be able to answer Golaud if he should question her. The moon breaks through the clouds and illumines brightly the interior, revealing three old and white-haired beggars asleep against a ledge of rock. Mélisande is uneasy, and would go. They depart in silence.
ACT III
The opening scene of the third act shows the exterior of one of the towers of the castle, with a winding staircase passing beneath a window at which sits Mélisande, combing her unbound hair, and singing in the starlit darkness—"like a beautiful strange bird," says Pelléas, who enters by the winding stair. He entreats her to lean further forward out of the window, that he may come closer, that he may touch her hand; for, he says, he is leaving on the morrow. She leans further out, telling him that he may take her hand if he will promise not to leave on the next day. Suddenly her long tresses fall over her head and stream about Pelléas. He is enraptured. "I have never seen such hair as yours, Mélisande! See! see! Though it comes from so high, it floods me to the heart!... And it is sweet, sweet as though it fell from heaven!... I can no longer see the sky through your locks.... My two hands can no longer hold them.... They are alive like birds in my hands. And they love me, they love me more than you do!" Mélisande begs to be released, Pelléas kisses the enveloping tresses.... "Do you hear my kisses?—They mount along your hair." Doves come from the tower—Mélisande's doves—and fly about them. They are frightened, and are flying away. "They will be lost in the dark!" laments Mélisande. Golaud enters by the winding stair, and surprises them. Mélisande is entrapped by her hair, which is caught in the branches of a tree. "What are you doing here?" asks Golaud. They are confused, and stammer inarticulately. "Mélisande, do not lean so far out of the window," cautions her husband. "Do you not know how late it is? It is almost midnight. Do not play so in the darkness. You are a pair of children!" He laughs nervously. "What children!"
He and Pelléas go out, and the scene shifts to the vaults in the depths under the castle,—dank, unwholesome depths, that exhale an odor of death, where the darkness is "like poisoned slime." Golaud leads his brother through the vaults, which Pelléas had seen only once, long ago. "Here is the stagnant water of which I spoke; do you smell the death-odor?—That is what I wanted you to perceive," insinuates Golaud. "Let us go to the edge of this overhanging rock, and do you lean over a little. You will feel it in your face.... Lean over; have no fear; ... I will hold you ... give me ... no, no, not your hand, it might slip.... Your arm, your arm! Do you see down into the abyss, Pelléas?" "Yes, I think I can see to the bottom of the abyss," rejoins Pelléas. "Is it the light that trembles so?" He straightens up, turns, and looks at Golaud. "Yes, it is the lantern," answers Mélisande's husband, his voice shaking. "See—I moved it to throw light on the walls." "I stifle here.... Let us go!" exclaims Pelléas. They leave in silence.