A forest near the castle of the brotherhood of the Holy Grail. The old knight Gurnemanz and two esquires perform their morning prayers, while other knights prepare a bath for their ailing ruler Amfortas, who suffers from an incurable wound. Suddenly Kundry appears, a mysterious, ageless woman, who serves as the Grail’s messenger. She has brought medicine for Amfortas. The king is carried in. He reflects on a prophecy that speaks of his salvation by the hands of a “pure fool, enlightened by compassion,” then is borne off. When the esquires ask about Klingsor, a sorcerer who is trying to destroy the knights of the Grail, Gurnemanz tells the story of Amfortas’s wound: the Holy Grail, the cup Christ drank from at the Last Supper, and the spear that pierced his body on the cross were given into the care of Titurel, Amfortas’s father, who assembled a company of knights to guard the relics. Klingsor, wishing to join the brotherhood, tried to overcome his sinful thoughts by castrating himself but was rejected. Seeking vengeance, he built a castle across the mountains with a magic garden full of alluring women to entrap the knights. Amfortas set out to defeat Klingsor, but was himself seduced by a “terribly beautiful woman” and stabbed by Klingsor with the holy spear, which he then took from Amfortas. The wound can only be healed by the innocent youth the prophecy has spoken of. Suddenly a swan plunges to the ground, struck dead by an arrow. The knights drag in a young man, who boasts of his archery skills. He is ashamed when Gurnemanz rebukes him, but he cannot explain his violent act or even state his name. All he remembers is his mother, Herzeleide, or “Heart’s Sorrow.” Kundry tells the youth’s history: his father died in battle and his mother reared the boy in a forest, but now she too is dead. Gurnemanz leads the nameless youth to the castle, wondering if he may be the prophecy’s fulfillment.
The knights assemble in the hall of the castle. Titurel bids Amfortas uncover the Grail to give strength to the brotherhood, but Amfortas refuses: the sight of the chalice increases his anguish. Titurel orders the esquires to proceed, and the chalice casts its glow about the hall. The nameless youth watches in astonishment but understands nothing. The ceremony ended, Gurnemanz, disappointed and angry, drives him away as an unseen voice reiterates the prophecy.
In his castle, Klingsor summons Kundry, who, under his spell, is forced to lead a double existence, to seduce the young fool. Having secured the spear, Klingsor now seeks to destroy the youth, whom he knows can save the knights of the Grail. Hoping for redemption from her torment, Kundry protests in vain.
The nameless youth enters Klingsor’s magic garden. Flower maidens beg for his love but he resists them. The girls withdraw as Kundry, transformed into a beautiful young woman, appears and addresses him by his name—Parsifal. He realizes that his mother once called him so in a dream. Kundry begins her seduction by revealing memories of Parsifal’s childhood and finally kisses him. Parsifal suddenly feels Amfortas’s pain and understands the idea of compassion: he realizes that it was Kundry who brought about Amfortas’s downfall and that it is his mission to save the brotherhood of the Grail. Astonished at his transformation, Kundry tries to arouse Parsifal’s pity by telling of the weary life she has been forced to lead ever since she laughed at Christ on the cross, but he resists her. She curses him to wander hopelessly in search of the knights of the Grail and calls on Klingsor for help. The magician appears and hurls the holy spear at Parsifal, who miraculously catches it in midair, causing Klingsor’s realm to perish.
Gurnemanz, now very old and living as a hermit near the Grail’s castle, finds the penitent Kundry exhausted in the forest. A strange knight approaches and Gurnemanz recognizes Parsifal bearing the holy spear. Parsifal describes his years of wandering, trying to find his way back to Amfortas and the Grail. Gurnemanz tells him that he has come at the right time: Amfortas, longing for death, has refused to uncover the Grail, the brotherhood is suffering, and Titurel has died. Kundry washes Parsifal’s feet, and Gurnemanz blesses him and proclaims him king. As his first task Parsifal baptizes Kundry. He is struck by the beauty of nature around them and Gurnemanz explains that this is the spell of Good Friday. The distant tolling of bells announces the funeral of Titurel, and the three make their way to the castle.
Knights carry the Grail, Amfortas on his litter, and Titurel’s coffin into the Hall of the Grail. Amfortas is unable to perform the rite. He begs the knights to kill him and thus end his anguish—when suddenly Parsifal appears. He touches Amfortas’s side with the spear and heals the wound. Uncovering the Grail, he accepts the homage of the knights as their redeemer and king and blesses them. The reunion of the Grail and spear has saved the community.