Offenbach is frequently considered to be a composer merely of operettas and other light musicals who produced only one truly serious piece: Les contes d'Hoffmann. The French composer, however, composed more than 650 works altogether, and his first opera, Die Rheinnixen (which includes the famous Barcarolle theme familiar from the later Hoffmann) has been unjustly forgotten.
The piece depicts a country shattered by internal warfare through an unusual love story. Composed with astonishing richness, this sparkling and glittering work combines poetry and politics, dreams and reality and the supernatural and the realistic. The work was given its Hungarian premiere in a production by Ferenc Anger.
At Hedwig's estate along the Rhine, preparations are under way for a harvest festival. The farmers and townsmen enjoy themselves greatly, even though the country is beset by a provincial war, and Hedwig is aware that enemy mercenaries are already prowling around the area. She curses the soldiers and the shame and grief that they bring. Her wise adviser, Gottfried, assures her of his support. Next to arrive is Hedwig's daughter, Armgard, who is asked by her mother not to sing lest she share the fate of those maidens who are bewitched by the fairies of the Rhine after singing too much. But Armgard, wishing to have fun and entertain the others, sings a ballad for the festive crowd. Hedwig then tells her that Gottfried has asked her for Armgard's hand in marriage. After emphatically rejecting this offer, she lets them in on her secret: her heart is already settled on none other than Franz, who has recently joined the mercenaries. Gottfried offers to find the girl's beloved for her. Just then, a farmer arrives with news: the soldiers are coming! Gottfried takes the women to seek refuge in the forest.
An army under the command of Conrad von Wenckheim approaches. Intoxicated with battle, they are now in search of wine and woman. Their great revelry is halted by the arrival of Franz, who is afflicted with a head injury and remains unable to recognise his native land. The lad, who has distinguished himself in the battle, collapses into a deep sleep. At Conrad's command, the local girls are assembled for the entertainment of the soldiers. Armgard, Hedwig and Gottfried are captured. The soldiers start to molest the girl and then bid her to sing. She then glimpses her beloved, but her joy turns to worry when she finds out that the lad is injured. Armgard sings Franz's favourite song from childhood, hoping that it will reach through to his troubled mind. But her plan is unsuccessful, and eventually she collapses, overcome by exhaustion and the harassment by the soldiers.
At Armgard's catafalque, a funeral dirge is heard. Hedwig bids farewell to her daughter, whose birth and death were both caused by criminal acts. She then reveals to Gottfried her hitherto closely guarded secret: Armgard's father was a soldier who deceived his way into Hedwig's bed, and the church wedding was only a sham. The grief-stricken mother heads into the forest to see her daughter one last time that night as she takes up the eternal dance alongside the Rhine fairies. Gottfried is about to go after her, but then Franz arrives: the shock has restored his memory now that his beloved is dead. In a sorrowful romance, he sings of his true emotions for Armgard. But the arrival of Conrad prevents him from being able to remain by his beloved's side: the army is ready to depart. All they need is a guide to enable them to strike at the enemy. Realising Gottfried's utility for this, two soldiers attempt to force him, first with threats of violence, and then with money, to aid them. After initially resisting them and motivated by thoughts of vengeance, Gottfried pretends to accept the money so that he can get the soldiers lost in the forest. They depart. Armgard, who had only seemed to be dead, then wakes up from her trance and rushes off to Franz's aid.
At the Elfenstein, Hedwig waits for her daughter's spirit to appear. The fairies sing in a chorus. Armgard arrives, seeking Franz. The two women see each other. Hedwig thinks she is looking only at her daughter's ghost, so it is as a ghost that Armgard attempts to convince her mother to return home while she herself continues on in search of her beloved. Left alone now, Hedwig is about to head home when Conrad and his force appear, together with Franz. Conrad entertains his troops with tales from his youth. Suddenly, Hedwig recognises Conrad as the man who tricked her: Armgard's father, he was also criminally responsible for her death. Hedwig swears vengeance. The fairies appear on the scene. Besotted with feelings of revenge, Hedwig watches as they take the men with them. Armgard also appears and, with her singing, entices her beloved out of the fairy ring.
The day of battle dawns. Returning to the mercenaries after having miraculously escaped from the fairies are Conrad and Franz. The latter attributes their escape to the intervention of his beloved, Armgard, or rather to the girl's ghost, and wishes to be united with her in death. Armgard herself appears and, after much difficulty, succeeds in convincing Franz that she really is alive, so Franz gives up his plan. A mercenary then leads in Hedwig, now a prisoner after being captured while stealing after the soldiers in search of vengeance. Led before Conrad, Hedwig rebukes him for everything he has done. Conrad begs her forgiveness and asks to meet his daughter. Hedwig, however, cruelly reveals that Conrad himself has taken the girl's life. In his grief, Conrad attempts to mend his ways and chooses peace over war. He sets Gottfried free and, in order to preserve his secret, the recently arrived Armgard and Franz as well. Alone, he prepares to confront the soldiers who are infuriated over the averted battle. Learning that Conrad is her father, Armgard is unwilling to leave him there. Everybody is in danger: on one side a great precipice awaits them, while on the other, the enraged mercenary horde is approaching. The fairy chorus appears in the flames of the exploding gunpowder. Now where will they lead our heroes?