In the first act, the lovers meet at a festival. Leandro, victor in the Aphrodisian games both as a swordsman and cytharist, is crowned by Hero. He sings two odes borrowed from Anacræon. Ariofarno, the archon, loves Hero. When he seeks to turn her from her sacred mission as priestess of Aphrodite she spurns his love. She invokes an omen from a sea shell, on the altar of the goddess, and hears in it rushing waters and the surging sea, that will eventually turn her romance to tragedy. When she kneels before the statue of Apollo and pleads to know her fate, Ariofarno, concealed, answers: "Death."
The second act takes place in the temple of Aphrodite. The archon claims that he has been warned by the oracle to reinstate a service in a town by the sea. He consecrates Hero to the duty of giving warning of approaching storms, so that the raging waters may be appeased by priestly ritual. He offers to release her from this task is she will return his love. When she again spurns him, Leandro attempts to attack him. For this, the young man is banished to the shores of Asia, while Hero sadly pledges herself to the new service.
In the third act, which takes place in a tower overlooking the Hellespont, Ero sings of her love for Leandro, punctuated by distant voices of sailors. As she sings, she sees him swimming toward her. Leandro emerges from the sea, climbs over the rocks to the window, and embraces her. The lovers sing their ecstasy. Meanwhile, a storm arises unobserved. The trumpet that should have been sounded by Hero is sounded from the vaults beneath the tower. Leandro throws himself back into the Hellespont while Ariofarno and his priests chide Hero for her neglect as they discover its cause. A thunderbolt shatters a portion of the tower, and Leandro's body is disclosed. Hero falls dying to the ground, while the archon rages.
Adapted from The Complete Opera Book by Gustav Kobbé and program notes by David Hamilton from the Complete Mapleson Cylinders album