Clara Hayes lives a miserable life bullied by her cruel stepmother Marlene and vain half-sister Stella, mainly because of a noticeable red birthmark under her left eye. Her only beloved grandma falls critically ill with a huge medical bill, forcing Clara into an arranged marriage with the supposedly old, disabled head of the wealthy Ashford family. Desperate before the wedding, she visits Velvet Mask Club under the alias Bella with a lace mask to hide her flaw, where she spends an unforgettable passionate night with a mysterious man calling himself Owen. Neither learns the other’s real identity that night.
One year passes. Clara lands a job as personal assistant to Julian Ashford, the young, powerful heir of Ashford Group. She never connects her cold, gentle boss with either the rumored elderly husband or Owen from the club, while Julian also fails to link his timid, hardworking assistant to the alluring Bella he cannot stop thinking about. Taking advantage of their mutual misunderstanding, Stella lies to Julian that she is his legal wife. She greedily demands luxury gifts and repeatedly sets up traps at the office to humiliate and frame Clara, with jealous coworker Serena helping her spread nasty rumors about Clara’s appearance and character.
Julian grows fond of Clara’s kindness and resilience and secretly protects her from harm. He gradually pieces together the truth that quiet Clara and masked Bella are the same woman. At the company’s grand banquet, Clara bravely removes the heavy makeup she uses to exaggerate her birthmark, revealing her naturally stunning face. Right then, Mr. Harlow the butler arrives with the official marriage certificate. Both Clara and Julian are stunned to discover they signed the marriage papers together long ago—they have been legitimate spouses this whole time. Stella’s false identity is fully exposed. All misunderstandings fade away. Julian pledges to hold a splendid wedding for Clara to make up for her painful past, and the two embrace to start their sincere, happy life together.