There Is Many Like Us (2015) on Netflix

Plot summary

During the German occupation of Warsaw, Max Fronenberg is sent to Pawiak Prison Camp, where he works as a sheet metal laborer. He meets Rena Rosenbaum, a young woman who keeps her Jewish descent hidden from the Germans and fears discovery; in desperation she gets a note to him revealing her true identity, hoping word will reach her family if anything happens to her. Max uses his standing as a valued worker and the connections he has made inside the camp to bring her warmer clothes, shoes and boots, and secures her a sewing position that shields her further. With executions and liquidations rising, Max fears his labor will not keep him alive, so he and two other prisoners begin digging an underground passage toward the city's sewer system.