ACT I
King Heinrich of Germany, in Antwerp to raise an army, calls on the Brabantian noble, Telramund, to explain why the country is wracked by strife. Telramund claims that his ward Elsa has murdered her brother, Gottfried, the heir of Brabant. Convinced of Elsa’s guilt, Telramund has given up his claim to her hand and married Ortrud, a sorceress. Elsa is summoned to defend herself and tells of a dream she has had of a knight who will be her champion and whom she will marry. Twice the herald calls on the knight to appear, but only after Elsa has added her prayer does Lohengrin arrive. He bids a sad farewell to the swan that has accompanied him and announces that he has come to vindicate Elsa and to be her husband—but that he will depart if ever Elsa should ask him his name or place of origin. Elsa agrees to these conditions. To establish her innocence, Lohengrin engages Telramund in single combat and emerges victorious.
ACT II
Scene 1 – Telramund broods on his defeat at the hands of Lohengrin and blames Ortrud for ensnaring him in her plot for the throne. Ortrud defends herself and convinces Telramund that Lohengrin won the battle through sorcery. When Elsa appears, Ortrud appeals to her pagan gods for help. As Elsa offers her friendship and forgiveness, Ortrud begins to sow the seeds of doubt in the mind of the bride.
Scene 2 – Joyful preparations are made for the wedding. As Elsa prepares to enter the cathedral with her bridal procession, Ortrud halts the festivities, claiming that the “nameless knight” is an imposter. Telramund accuses Lohengrin of sorcery. Elsa assures her champion of her faith, but the poison of doubt has begun its work. King Heinrich leads the couple into the cathedral.
ACT III
Scene 1 – In their bridal chamber, as Lohengrin and Elsa declare their love for each other, Elsa’s anxiety heightens. Seized by a growing need to know his identity, she begs him to reveal his name and origin. Suddenly Telramund and his henchmen invade the chamber, intending to kill Lohengrin. Telramund is slain by Lohengrin. Sadly leaving Elsa in the dare of her attendants, Lohengrin orders the nobles to bear Telramund’s body to the King and tells Elsa that he will meet her there to answer her questions.
Scene 2 – As King Heinrich gathers the armies to prepare for the coming battle, Telramund’s body is brought before him. When Elsa arrives, distraught and unable to speak, Lohengrin reveals Telramund’s treachery. He declares that he is Lohengrin, son of Parsifal. As one of the sinless warriors who guard the Holy Grail, it is his duty to go forth into the world to defend those who are beset by evil. He announces that he was sent to be Elsa’s champion and restore the rightful ruler of Brabant to his throne. Elsa’s promise having been broken, he must now return the guardianship of the Grail. Predicting victory for the King’s forces, Lohengrin bids Elsa a sorrowful farewell as the swan that brought him again nears the shore. Ortrud rushes in declaring that the swan is in actuality Elsa’s brother, Gottfried, on whom she has placed a spell. She rejoices over Elsa’s betrayal of Lohengrin, the one man who could have broken the spell. Lohengrin prays and the swan vanishes; in its place stands Gottfried.