Guillermo, a middle-aged young man, is walking down the street when he hears a woman singing through a door phone. Captivated by that voice, he wants to meet the woman behind it but he is in a hurry and they meet for the next day. The young man returns but something happens while he listens to the voice and although he doesn't know her apartment he decides to go in to save her from a supposed danger without knowing that he will no longer be able to leave that place.