Warsaw, 1981. British academic Joan Andrews (Lesley Manville) is visiting a Polish university when a violent political protest erupts. Caught up in the ensuing chaos, she witnesses a brutal murder by the secret police and captures the evidence on her Polaroid camera. Now trapped behind the Iron Curtain, Joan is thrust into a deadly game of espionage involving student rebels and government operatives, where no one can be trusted and the consequences could spiral into World War III.