I read a book about the same situation, but the movie is definitely very good, too.
This is during the second world war and there's 511 POWs in a Japanese camp in the Philippines. They're the ones left from the Bataan Death March, and at this point, it's been three years. We see it from three views: the POWs, the rescuing folk, and the underground group.
These groups are shown in a thread on how things get done and how they meet up in the end. There's lots of ugly things that happen and we see, but the push to get our men out really pulls you to watch.
The first part of the credits shows real video from when the POWs come out of the camp, are taken to the sea, on a ship, getting home, and in a parade. That part made me cry. I really liked this.