The play unfolds on the terrace of Herod's palace above the banquet hall. A gigantic staircase stands to the left; a cistern surrounded by a wall of green bronze appears at the back. The Young Syrian exclaims how Salomé is beautiful tonight. It is as if she was dancing. "Look at the moon!" cries Herodias' Page, comparing it to a woman rising from her tomb, a woman "looking for dead things." He warns the Syrian that he looks at the princess too much. A noise is heard in the hall, and the Soldiers complain that the Jews are howling again about their religion. The First Soldier observes that the Tetrarch (King Herod) has a "somber look," and the soldiers wonder at whom he is looking.
Suddenly the voice of Jokanaan is heard from the cistern, proclaiming the coming of the Messiah: "The eyes of the blind shall see the day, and the ears of the deaf shall be opened." The First Soldier explains to the Cappadocian that Jokanaan is a prophet from the desert. It is impossible to understand what the prophet says, and the Tetrarch has forbidden the prophet being seen. The Cappadocian remarks that the cistern must make an unhealthy prison. The Second Soldier protests: Herod's elder brother, Herodias' first husband, lived there for twelve years without dying. Ultimately he had to be strangled by Naaman, the Negro executioner, bearing Herod's death-ring.
The Syrian exclaims that Salomé approaches. She enters, insisting that she cannot stay with Herod looking at her all the while "with his mole's eyes under his shaking eyelids." To the Page's horror, the Syrian invites her to sit. Salomé welcomes the moon, cold and chaste, with a virgin's beauty. Jokanaan again announces the coming of the Lord. Salomé asks if he is the prophet Herod fears, the prophet who maligns her mother. As Jokanaan preaches on, Salomé insists that she speak to him. All attempt to dissuade her. She plies the Syrian to bring the prophet forth.
The prophet emerges, and Salomé looks at him. Salomé exclaims that the prophet's eyes are terrible above all, like "black lakes troubled by fantastic moons." He is a wasted "ivory statue," chaste like the moon. "Who is this woman who is looking at me?" protests Jokenaan, bidding Salomé begone. Salomé implores the prophet to speak on: his voice is like wine. She is "amorous of his body." Jokanaan curses her anew. Begging Salomé to stop, the Syrian kills himself and falls between the prophet and princess. Salomé continues to ask Jokanaan to let her kiss him. He orders her to seek the Lord, refuses to look upon her, and descends into the cistern.
The First Soldier insists that they transport the body lest Herod see it. Suddenly the court enters, and Herod calls for Salomé while Herodias reproaching him for always staring at her. Herod muses on the "strange look" of the moon, comparing her to a drunken madwoman looking for lovers. Herodias replies that the "moon is like the moon, that is all" and bids him inside. Herod refuses, calling the servants to bring the festivities outside. Herod slips on the blood of the Syrian and gasps at the ill omen. The Soldiers feign that they do not know why he killed himself.
Jokanaan announces that what he has foretold has come to pass. Herodias asks Herod to silence the prophet, since he is forever "vomiting insults" against her. Herod most certainly fears him, and that is the main reason that he does not deliver him to the Jews. Herod replies that the prophet is a holy man who has seen God. A Jew rejoins that God has hidden himself, and thus evil has come upon the land. Jokanaan announces the coming of the "Savior of the world." A Nazarene declares that Jokanaan speaks of the Messiahs who works miracles. Herodias scoffs. Jokanaan curses the daughter of Babylon with "golden eyes" and "gilded eyelids," annoucing her death by stoning, by the piercing of her body with swords, its mashing under shields. Herodias is enraged that Herod would let Jokanaan slander her: she is his wife. Herod changes the subject, proposing that all toast Caesar.
Increasingly distractedly by Salomé, Herod asks his daughter to dance for him. She refuses. He beseeches her, swearing to give her whatever she wishes. Salomé dances. Herod invites Salomé to ask for her reward, and she asks for the head of Jokanaan in a silver charger. Herodias applauds her. Aghast, Herod begs her to be reasonable. He offers her an emerald from Caesar that, if looked through, has telescopic properties. Salomé continues to demand Jokanaan's head. Herod rejoins that Salomé only asks to punish him for looking at her. He will look no more, at neither things nor people. "Only in mirrors should one look, for mirrors do but show us masks." He offers the implacable Salomé his flock of white peacocks with feet of gilded gold. Salomé is unmoved. Herod protests that Jokanaan might be a holy man and has foretold disaster on the day of his death. He offers all his hidden jewels; he would even give her the veil of the sanctuary to be released from his word. Salomé refuses.
Herod falls back and the Soldier bears his death ring to the frightened Executioner. Moments later, a huge black arm emerges from the cistern, bearing Jokanaan's head on a silver shield. Salomé seizes it and tells the head that she will kiss its mouth now. But she wonders why Jokanaan refuses to look at her. He saw his God but never saw her. She hungers for his body, and nothing will quench her. She was a virgin, and she took his virginity. If he had looked at her, he would have loved her, and love's mystery is greater than death's.
Herod declares Salomé monstrous. Herod refuses to stay and calls for the servants to put out the torches. He will not look at things nor suffer them to look at him. "Put out the torches! Hide the moon! Hide the stars!" he exclaims. Herod begins to climb the staircase to the palace, and the stage goes dark. The voice of Salomé announces that she has kissed the prophet's mouth. It tastes bitter, perhaps of blood or love. A moonbeam falls on Salomé, covering her with light. Herod turns and, upon seeing Salomé, orders the soldiers to kill her. They rush forward and crush her beneath their shields.