Le Trou
I do love a good prison movie, and this is no exception. What makes it so great is that it's based on a true story, and even more interestingly, they cast one of the real prisoners involved in the escape. It focuses on all the steps it took to escape, more than most prison films and really shows the hard labour required to break out. It also portrays the new inmate's betrayal very well. This is a fantastic film that I highly recommend. (5th film)