Le Cahier bleu is a bande dessinée album created by André Juillard in 1994.
[1] Chapter 1 tells the story of two friends, Victor and Armand, who see a young lady, Louise, in her flat whilst the Paris Métro has broken down just outside.
Chapter 1 ends by Louise discovering a diary, Le Cahier bleu, in her post box.
Chapter 3, opens with Pauline, Louise's older sister, and Victor in the Juge d'Instruction's.
Victor then storms to Armand's flat and confronts him about planting the diary in Louise's post box.