The night before her marriage, the very beautiful opera singer Malvina is murdered on stage, in front of her public. The disturbing Docteur Droz takes her corpse to a strange and gigantic dwelling by the ocean, where he makes musical automata. He takes on a piano tuner, Felisberto, to look after his mechanical objects. Guided by a seductive and maternal housekeeper, the ingenuous and gentle Felisberto is astonished to discover the purpose for which he has been employed, and the doctor's unusual world: the servants, the woods, the sea, the automata, are all very strange, and full of mystery. Every evening, the piano tuner hears a bewitching song, whose source he cannot work out. Determined to solve this mystery, he follows the voice, and furtively discovers Malvina, whom the doctor has brought back to life. When out for a walk, he finds her sitting on a bench facing the sea; she seems absent, hardly speaks, and Felisberto gradually realizes that their host has decided to make her the star attraction of a diabolical opera, with her performing alongside a cast of automata. Moved by the young woman's beauty and vulnerability, he resolves to do everything he can to free her.