Parasite
After the poor Kim family attempt to escape poverty by secretly infiltrating the home of the wealthy Parks, a series of events leads them to uncover a dark secret: the Parks' former housekeeper, Moon-gwang (Lee Jeong-eun), has been hiding her husband in the basement. In the end, a backyard birthday party becomes the site of a bloody massacre, forcing the Kim patriarch, Ki-taek (Kang-Ho Song), into hiding. The final twist reveals that Ki-Taek has been living in the now-vacant basement of the Park home.