The silent sin - Anja Sicking

When Anna's fortune is lost, she is forced to become a maid for music publisher De Malapert. Intrigued by her employer, she spends her free time conjuring up ways to impress him.
However, De Malapert remains unaware of her attentions. Working in the shop by day and transcribing opera scores by night, he is distracted only by the occasional visit from his flamboyant friend Everard Borgholt.

As Anna's obsession deepens, however, she begins to eavesdrop on these late-night soirees. Unwittingly, she contributes to the downfall of both the "only man she could imagine giving herself to" and herself.