In 1943 Germany decided to clear the ghetto by sending all the Jews to concentration camps. This gave Leopold the opportunity of a lifetime. A rich Jew, Ignacy Chiger, offered him 500 Zloty a day to hide a group of Jews in the sewers. At first Chiger tries to store 20 Jews, but Socha persuades him that it isn't possible to hide and feed more than 10 Jews without fear of them being discovered. The months pass by and Chiger runs out of money, but by that time Socha has found compassion and he continues to hide the Jews for free. They remain in the sewers until the Russians "liberate" Lwow in 1944. (Russia annexed eastern Poland including Lwow after the war, and the Jews had to flee to escape Russian persecution).
This is a dark claustrophopic film, obviously. At times it's chaotic, with people talking in a mix of German, Polish and Russian. The film has been compared with "Schindler's List", an obvious comparison, but "In Darkness" is much more dramatic. It's a lot darker and more morbid than anything Steven Spielberg has ever made. There are no real heroes, everyone is tainted.