[3] Although the opera depicts spectacular scenes on the ocean, a creole carnival and an exploding volcano, the plot is essentially "an intimate romantic drama about young people in love, all the more poignant because of its pointlessness".
[7] The Spectator defended the composer against those who criticised him for writing in part tunes in a "Strauss-Puccini idiom", also praising Williamson's character music, the dances and for having "an accent and palmprint of his own".
[10] 3 flutes (2 double piccolo), 2 oboes and cor anglais, 2 clarinet and bass-clarinet, 2 bassoons and contra-bassoon, 4 horns, 4 trumpets, 3 trombones, 1 tuba, timpani, percussion, organ, 2 harps, strings Stage Music: flute, clarinet, two horns, four trumpets, three violins, one double bass[13] In the Prologue, set in the present day, a band of fishermen in the Caribbean casting their nets hear the sound of violins in the distance.
The old fisherman tells the others of the legend of the submerged island which rises from the sea to the ghostly sounds of carnival violins on Shrove Tuesday, the day on which it was destroyed by a volcano.
Sosthène, son of the Count de Serindan, is recently returned from France, and expresses his joy to be back on the island and especially his passion to see again his cousin Berthe; she however still looks on him as a child.
However, Sosthène has found out that Marcel is married already; and he notes their absence, he persuades Berthe to leave the villa determined to find the lovers and stop them eloping.
Sosthène tells her to row out to a ship moored off shore in case the fleeing lovers are planning to head for there; meanwhile he will seek them by horse, and that way they can prevent Josephine from leaving the island.
Berthe, who as planned had rowed out into the harbour to intercept the two runaways is now the only person alive, and in the final scene at dawn she remembers Saint-Jacques and laments all those she loved.