You're the one being tricked.

1930s Korea, in the period of Japanese occupation, a new girl, Sook-hee, is hired as a handmaiden to a Japanese heiress, Hideko, who lives a secluded life on a large countryside estate with her domineering Uncle Kouzuki. But the maid has a secret. She is a pickpocket recruited by a swindler posing as a Japanese Count to help him seduce the Lady to steal her fortune.