This movie is inspired by Chinese superstitions and their spooky rituals. It focuses, though, about the gate of hell being opened in the seventh lunar month of the Chinese calendar and then the spirits will come out -- to scare people, most probably. That's what they usually do.
The storyline isn't really something most of us haven't seen before, and it has the usual tricks up the sleeves of horror filmmakers, like the passing shadows, musical crescendos, creaking furniture, and close up fast cuts. The plot was somewhat complicated, but it did it's job as a horror movie to me, making me hold my breath from beginning to end. It delivered some good scares even when it’s most expected. And i did scream. I seldom scream when i watch horror movies. But The Maid made the other horror movies i've watched seem funny to me.