A solemn bridal march opens the next act, while the maids of honour conduct Elsa and Lohengrin to the bridal chamber. There, after a love scene of enchanting beauty, her doubts break forth once more. 'How is she to know,' she cries, 'that the swan will not come some day as mysteriously as before and take her beloved from her arms?' In vain Lohengrin tries to soothe her; she will not be appeased, and in frenzied excitement puts to him the fatal question, 'Who art thou?' At that moment the door is burst open, and Telramund rushes in followed by four knights with swords drawn. Lohengrin lifts his sacred sword, and the false knight falls dead at his feet. The last scene takes us back to the banks of the Scheldt. Before the assembled army Lohengrin answers Elsa's question. He is the son of Parsifal, the lord of Monsalvat, the keeper of the Holy Grail. His mission is to succour the distressed, but his mystic power vanishes if the secret of its origin be known. Even as he speaks the swan appears once more, drawing the boat which is to bear him away. Lohengrin bids a last farewell to the weeping Elsa, and turns once more to the river. Now is the moment of Ortrud's triumph. She rushes forward and proclaims that the swan is none other than Godfrey, Elsa's brother, imprisoned in this shape by her magic arts. But Lohengrin's power is not exhausted; he kneels upon the river bank, and in answer to his prayer the white dove of the Grail wheels down from the sky, releases the swan, and, while Elsa clasps her restored brother to her breast, bears Lohengrin swiftly away over the waters of the Scheldt.