[Derek]

Dark City rocks. It most often is compared to the movie Metropolis (which I unfortunately haven't seen).

Brief summary: A guy wakes up in a hotel room with no memories. Plagued by confused, half-remembered memories of a bright sunny childhood, he struggles through a (shocker) dark city trying to find out who he is and what's going on. Throughout the entire movie, the city is always dark; no sun, no moon, just dim streetlights. He eventually discovers that the city is a massive experiment run by aliens who constantly rearrange the structure of the city and the lives of the people in it. His main interactions throughout the movie are with his wife, a police inspector who believes him to be guilty of the murder of a number of prostitutes, and a defecting collaborator working with the aliens to alter people's minds.

There's more to the movie than that though, and I highly recommend it for anyone interested in just a good scifi film. It's not really horror, so it doesn't quite fit the Halloween theme exactly, but it's very dark.

And on a side note, I think this fiver is my 94th-ish fiver or so, which is 47x2, so I'm glad to do one of my favorite movies in honor of the occasion (though I didn't realize it at the time).