What does a pregnancy test have to do with a Chinese prison? Not much, at first glance. However, filmmaker Laetitia Moreau found a handwritten letter from a political prisoner next to the package insert of the pregnancy test purchased in a Paris pharmacy. The letter describes the forced labor he was doing in the prison where the test was manufactured. The letter begins like this: "Dear friends, do you know that Chinese prisoners in Tianjin have to work 12 to 15 hours a day and don't even get a meal in return so that you can have a comfortable life?" He concludes with the words: "Please help me." The letter is rare testimony to the fact that in China it is not only the Uyghurs who are subject to forced labor. Prisoners are exploited by subcontractors working for both Chinese and foreign companies. They are beaten and tortured. In Mao's time, there were re-education camps for dissidents, but the current government is pursuing other goals: It is striving for economic supremacy and has introduced slave labor into the country's prisons to help achieve this. When Laetitia Moreau received the letter in question, she set off to China to meet with former prisoners. Recently released, the former inmates talk about the hell they lived through and describe the mechanisms of the system. Finally, Moreau makes her way to the huge prison complex where the letter was written.