While still relegated to the archive department, Chloe is called in by Rocher to investigate the disappearance of Arthur, eight years old. And with good reason: the boy, who disappeared when leaving school, goes to the same school as Lili. The video surveillance footage Hyppolite recovers shows the child peacefully following his teacher, whose identity and address turns out to be false. When the team finds out the kidnappers had at one point been planning to abduct Lili, Chloe has to draw on all her strength to keep from letting guilt impair her analytic abilities. …