The film follows different groups of explorers as they head into sewers, castles in Scotland, the catacombs in Paris, and an old missile base in Florida, just to name a few. There are also interviews with explorers and some nice photographs which flesh out the sometimes dark film footage.
It's an interesting film and I enjoyed it. But it didn't completely grab me and I can't put my finger on exactly why. Still I would recommend it to anyone seeking to learn about urban exploring.