This is the kind of pure genius that comes along only rarely. I watched it 3 times and never got tired of watching. I don't normally enjoy horror or thriller films, but this one is different. I was reminded of black and white Hitchcock as I was kept on the edge of my seat the entire time. This was in part due to the appropriately used and not overdone cinematography. Each scene is gorgeous and eerie to fit the film. I kept wanting to go back and re-play pieces (but resisted) because it was so captivating. Films like this come along only on rare occasions. The suspense builds from a standstill to a New York Subway as it progresses and the ending is an explosion of unexpected glee.