If I Sleep for an Hour, 30 People Will Die (2016)

He spent hours figuring out how to remove stains, then read chemistry textbooks and did experiments at home. In the summer of 1943, he and his family were arrested and sent to Drancy, the internment camp for Jews near Paris that was the last stop before the death camps. When the agent told Adolfo that they were struggling to erase a certain blue ink from the documents, he advised using lactic acid, a trick he’d learned at the dairy.

Source: www.nytimes.com