Basically the fil is about a small town, at midnight everyone falls asleep and has memorys and stuff changed,

There is one guy that isn't affected at midnight and is aware that peoples memorys are being changed, he is the prime suspect in a murder case, and has been framed

At the end of the film, it turns out the whole world is just an experiment by aliens

Please help I really want 2 watch it again but obviously cannot with out the title!

Thank you in advance :p

Dark City.

I put off seeing this for years and knew little about it, so I was unspoiled as to the big twist reveal. Finally, I'm watching it at my brother's house, and my sister-in-law walks in halfway through and goes, "Oh, is this the one where they find out they're all on an alien ship?" D'oh!

The end theme is pretty kick-, by the way.