Secret Door.

Ham Jae-kyeong, a successful adult web novel writer, suddenly finds herself in a slump. She rewrites her writing and characters keep overlapping. Se-hee, the CEO of a web novel company, is Jae-kyeong’s friend. Se-hee suggests to Jae-kyeong that she write a SM novel as a way to overcome her slump. At first, she refuses, but after being persuaded by her assistant writer, Gi-dong, she meets Seong-soo, who enjoys SM play. Jae-kyeong is drawn to the handsome and well-mannered Seong-soo. Is he researching for her novel or is he in a relationship? Growing increasingly captivated by Seong-soo’s charm, she begins to embrace SM play.