The Second Woman description:

Hui Bao is an actress rehearsing for a performance in a theater play alongside her boyfriend Nan. Falling sick and being unable to perform in the play, her twin sister Hui Xiang replace her as an act of kindness. However, Hui Xiang performs outstandingly eventhough having no drama training. Hui Bao starts to suspect that her twin sister has a romantic interest in her boyfriend, and it drives a wedge between the them.