Act I
Antwerp, first half of the 10th century. In Antwerp, on the banks of the Scheldt, a herald announces King Heinrich, who asks Count Telramund to explain why the Duchy of Brabant is torn by strife and disorder. Telramund accuses his young ward, Elsa, of having murdered her brother, Gottfried, heir to Brabant’s Christian dynasty. (Gottfried was actually enchanted by the evil Ortrud, whom Telramund has wed.) When Elsa is called to defend herself, she relates a dream of a knight in shining armor who will come to save her. The herald calls for the defender, but only when Elsa prays does the knight appear, arriving in a boat magically drawn by a swan. He pledges his troth to her on condition that she never ask his name or origin. Defeating Telramund in combat, the newcomer establishes the innocence of his bride.

第一幕
安特衛普，10世紀上半葉。在安特衛普的施凱爾特河畔，一名使者正在傳達國王海因裡希的命令，要求特拉蒙德伯爵解釋為什麼布拉班特公國會飽受衝突與動亂之苦。特拉蒙德指控年輕的領主艾爾莎謀害了自己的弟弟，即布拉班特王朝的繼承人戈特弗裡德。（實際上戈特弗裡德中了邪惡的奧特魯的魔法，奧特魯是特拉蒙德的妻子。）艾爾莎被招來為自己辯護，她提起自己曾在夢中見過一位騎士，他穿著閃亮的盔甲，並願意為她而戰。使者召喚守護人，但沒有用，但是當艾爾莎祈禱時，騎士才神奇地乘坐由天鵝拉的小船出現。騎士願意履行諾言，但有一個條件，就是要艾爾莎永遠不問他的姓名和出身。騎士在決鬥中打敗了特拉蒙德，還了自己的新娘一個清白。


INTERMISSION
中場休息


Act II
Before dawn in the castle courtyard, Ortrud and the Telramund swear vengeance. When Elsa appears in a window, Ortrud attempts to sow distrust in the girl’s mind, preying on her curiosity, but Elsa innocently offers the scheming Ortrud friendship. Inside, while the victorious knight is proclaimed guardian of Brabant, the banned Telramund furtively enlists four noblemen to side with him against his newfound rival.

At the cathedral entrance, Ortrud and Telramund attempt to stop the wedding—she by suggesting that the unknown knight is in fact an impostor, he by accusing Elsa’s bridegroom of sorcery. The crowd stirs uneasily. Though troubled by doubt, Elsa reiterates her faith in the knight before they enter the church, accompanied by King Heinrich.

第二幕 
黎明前，在城堡的院子裡，奧特魯和特拉蒙德發誓要報仇。艾爾莎出現在窗前時，奧特魯利用她的好奇心，設法在她心裡埋下了懷疑的種子，但天真的艾爾莎還把詭計多端奧特魯當成朋友。城堡裡面，獲勝的騎士被宣佈成為布拉班特的守護者，而已遭放逐的特拉蒙德偷偷召集了四個貴族來幫助他對付新的對手。

教堂入口，奧特魯和特拉蒙德企圖阻止婚禮——奧特魯說這位來歷不明的騎士實際上是個騙子，而特拉蒙德則控訴艾爾莎的新郎會巫術。人群開始騷動不安。艾爾莎雖然滿心疑慮，但在國王海因希裡的陪同下進入教堂之前，她反復重申，自己相信騎士。


INTERMISSION
中場休息


Act III
Alone in the bridal chamber, Elsa and her husband express their love until anxiety and uncertainty at last compel the bride to ask the groom who he is and whence he has come. Before he can reply, Telramund and his henchmen burst in. With a cry, Elsa hands the knight his sword, with which he kills Telramund. Ordering the nobles to bear the body to the king, he sadly tells Elsa that he will meet her later to answer her questions.

Escorting Elsa and the bier to banks of the Scheldt, the knight tells the king he cannot now lead the army against the Hungarian invaders. He explains that his home is the temple of the Holy Grail at distant Monsalvat, to which he must return; Parsifal is his father, and Lohengrin is his name. He bids farewell and turns to his magic swan. Ortrud rushes in, jubilant over Elsa’s betrayal of the man who could have broken the spell that transformed her brother into a swan. 

But Lohengrin’s prayers bring forth Gottfried in place of his vanished swan, and after naming the boy ruler of Brabant, Lohengrin disappears, led by the dove of the Grail. Ortrud perishes, and Elsa, calling for her lost husband, falls lifeless to the ground.

第三幕
房中只剩下艾爾莎和她的新婚丈夫時，兩人互訴衷腸，但在焦慮和不安情緒的驅使下，新娘最終向新郎問起他到底是誰，從哪裡來。新郎還沒開口，特拉蒙德就帶著自己的心腹闖了進來。艾爾莎驚叫一聲，把劍遞給騎士，騎士揮劍刺死了特拉蒙德。他命那幾個貴族把特拉蒙德的屍體帶到國王跟前，然後傷心地告訴艾爾莎，他晚些時候再來見她，回答她的問題。

騎士將艾爾莎和特拉蒙德的棺材送到施凱爾特河畔後，便告訴國王，自己不能帶領軍隊抵禦匈牙利的入侵了。他說自己的家在聖杯神廟，位於遙遠的蒙沙瓦特，而現在他必須回去了；他的父親是帕西法爾，而他自己叫羅恩格林。向眾人道別後，他召來了那隻可施展魔法的天鵝。奧特魯闖了進來，艾爾莎背叛了騎士，這讓奧特魯興奮不已。艾爾莎的弟弟就是因為她的魔咒才變成了天鵝。這個魔咒差點就要被騎士打破了。

但羅恩格林透過禱告讓戈特弗裡德擺脫了變成天鵝的魔咒。在宣佈戈特弗裡德要成為布拉班特的統治者後，羅恩格林在聖杯鴿的引領下消失了。奧特魯死了。而艾爾莎則呼喚著離她而去的丈夫，倒地死去了。