If I fall in love with you, I'll lose everything… Rosemary, who is raising her late brother and sister-in-law's child, receives news from her late sister-in-law's brother, billionaire Nicholas. Why does he want to see her now while he didn't even show up at his sister's funeral? He looks at Rosemary with eyes as cold as the Dark Lord's and declares that he will take the child, his blood relative and only heir. But Rosemary doesn't want to give the child to a man who thinks only about money. Rosemary refuses, but Nicholas tells her that he will hire her as a nanny as long as she promises not to marry or fall in love with anyone until the child has grown up.