Pauline and her gang investigate: Laure's secret

Autumn 1940: occupied Alsace under the German boot following France's defeat and the armistice signed in June 1940. Mathias and the twins Luc and Louis have set up their headquarters in the attic of their warlord Pauline's apartment building, a life-saving cocoon for these young teenagers deprived of their freedom. But one evening, against all odds, the discovery of a blood-stained mattress disrupts their joyous get-together, a disruption that turns into panic when a ghostly shadow enters their secret hideaway. That's all it takes for our foursome to launch a commando operation to unravel the mystery: who does the blood belong to? Who is this Laure we meet at the turn of a staircase or a street, and why has she returned to Sainte-Marie-aux-Mines? It's all a bit confusing... The mission promises to be a perilous one, as the Nazis are ruthless enemies. Will our young hotheads be able to solve the enigma without putting themselves in danger?