The curtain rises upon a rustic chorus, after which Dinorah appears, seeking her goat, and sings a slumber-song ("Si, carina, caprettina”) which is very graceful, and concludes with phrases in imitation of birds.  In the next scene, Corentin, the bagpiper, who has been away three months, and is nearly dead with terror of goblins and fairies, returns to his cottage, and to reassure himself sings a very quaint and original song ("Sto in casa alfine"), to the accompaniment of his pipe.  Dinorah suddenly appears and enters the cottage, and much to his alarm keeps him playing and singing, which leads to a very animated vocal contest between her and the bagpiper.  It is abruptly terminated, however, by the arrival of Hoeel.  Dinorah makes her escape by a window, and Hoeel relates to Corentin the story of the Korigans’ treasure.  As the first person who touches it will die, he determines that Corentin shall be his messenger, and to rouse his courage sends for wine.  While Corentin is absent, Hoeel sings an aria ("Se per prender”) which has always been a favorite with barytones.  After Corentin returns, the tinkling of the goat’s bell is heard.  Dinorah appears in the distance, and a charming trio closes the act, to the accompaniment of the whistling wind and booming thunder on the contra basses and drums of the orchestra.

The second act opens with a drinking-song by wood-cutters, and as they withdraw, Dinorah enters, seeking Hoeel.  She sings a tender lament, which, as the moonlight falls about her, develops into the famous “Shadow Song,” a polka mazurka, which she sings and dances to her shadow.  The aria, “Ombra leggier,” is fairly lavish in its texture of vocal embroidery, and has always been a favorite number on the concert stage.  The next scene changes to the Val Maudit (the Cursed Vale), a rocky, cavernous spot, through which rushes a raging torrent bridged by a fallen tree.  Hoeel and Corentin appear in quest of the treasure, and the latter gives expression to his terror in a very characteristic manner, with the assistance of the orchestra.  Dinorah is heard singing the legend of the treasure ("Chi primo al tesor"), from which Corentin learns that whoever touches it first will die.  He refuses to go on, and a spirited duet ensues between them, which is interrupted by the entrance of Dinorah and her goat.  Hoeel, fancying it is a spirit sent to keep him back, sings a very beautiful aria ("Le crede il padre").  The act closes with the fall of Dinorah, who attempts to cross the bridge, into the torrent, and her rescue by Hoeel, to the accompaniment of a storm set to music.  The scene, though melodramatic, is very strong in its musical effects.