Ji-Sun (Uhm Ji-Won) and her physician ex-husband are fighting over custody of their daughter Da-Eun. While trying to perform her job at a PR company, Ji-Sun juggles time with her daughter and winning her difficult custody battle. Ji-Sun recently hired a Korean-Chinese nanny, Han-Mae (Kong Hyo-Jin), to help watch over Da-Eun.
One evening, Ji-Sun comes back home from work, but Han-Mae and Da-Eun are not there. Ji-Sun desperately searches for her daughter. The outcome of her custodial battle and job commitments linger in the background. Meanwhile, Han-Mae's story is slowly revealed.