Lust, Caution by Alexandre Desplat.

It's sad people only talk about how ranchy the sex scenes were. It's an incredibly well-made film. Script, acting, cinematography, ... Everything is top-notch. Not to mention the score.

Desplat is always a good choice for a period drama, but his work here is another level. The score is so beautiful and nuanced like the film itself. It just perfectly fit to the tone of it.