Five years ago, Noh Seo-yoon, the eldest daughter of the Noh Won Group, was kicked out of her house after getting pregnant from a one-night stand with a strange man at the Lumina Hotel due to a conspiracy by her stepmother and stepsister. While living a difficult life raising twins alone, she caught the eye of Choi Yeo-jeong, the chairperson of Vision Tech who was disguised as a cleaner, and entered into a high-speed marriage with her son, Lee Hyeon-woo. Because of Lee Hyeon-woo and Choi Yeo-jeong, who hide their identities, Noh Seo-yoon suffers all kinds of contempt from her colleagues and stepsister, but she holds on steadfastly while developing feelings for Hyeon-woo. All without even dreaming of the fact that Lee Hyeon-woo is that strange man from the Lumina Hotel five years ago...