Bunker of the Dead (2015) on Netflix

Plot summary

Markus and Thomas have an old Jewish diary whose instructions they believe will lead them into Cerusit, a World War II complex beneath Bavaria that the Nazis ran as a secret research institute. Rumors about gold lost since the Third Reich still surround the site, and the two friends want to get inside. The way down, however, runs through ground the U.S. military controls, so Markus goes in alone with a camera and a radio to find the opening. His entry draws attention from the soldiers above, and something below has gone without food for more than seventy years.