This movie is based on a True Story. During World War 2 in France, some german soldiers are using a bunker to store food and medical supplies and use french civilians to work there. There's an air raid and the bunker entrances are completely caved in killing the germans and trapping the french. They attempt to dig but after a few days come to realise its hopeless as they are under about 200 feet of concrete. They start to live off the supplies and have a large supply of candles. After about 3 months they run out of candles and for the next 3 years live in total darkness (the war ends in between that time), workmen on the surface looking to build some structure find them by accident.

The Blockhouse (http://www.imdb.com/title/tt0069803/)

That's it, thanks.

You're welcome.