Too Beautiful to Lie (2004)

Young-ju's professional skills of pretense and deceit easily get her out on parole. On a train en route to her sister's wedding, she runs into Hee-chul, mistaking him for a bum trying to molest her. On top of that, a pickpocket steals Hee-chul's engagement ring. Young-ju is worried that she might be accused of the theft, so she sets out to retrieve the ring, but amid the hassle, she's left behind on the platform and can only watch the train leave with her luggage. Young-ju finds her way to Hee-chul's home and the family - seeing the ring - thinks she is Hee-chul's fiancée. To wiggle herself out of the situation without adding another crime to her rap sheet, she uses the skills of her profession and cons everyone into believing indeed she's the one. Meanwhile, Hee-chul returns home without having proposed to his girl for lack of a ring, and finds that his family, and in fact the whole town, now scorn him for his desertion of an innocent woman.