Kim Taeyeon has liked Tiffany Hwang since they met, and the feeling has eventually become mutual. However, Tiffany is a strict Christian and is fully aware that such a relationship is forbidden. The religious girl tried to forget these "impure" desires but to no avail. Tiffany accepted Taeyeon's declaration of love, but in one condition, no one else should know about their relationship.

One day, Taeyeon visits 'Maid in Heaven', a cafe-bar served by young women in maid outfits, and meets a girl by the name of Jessica.