Sarah brings the alarming message on Katie's phone to the police, hoping it will push the investigation forward. Yet when she tries to show it again, the message has mysteriously disappeared. The uncertainty deepens doubts about what really happened the night Katie vanished.

As Captain Jerome Ricard and Lieutenant Virginie Taylor continue their inquiries, Sarah begins her own search through Saint-Michel. At a local bar she learns that Katie was seen on the night of her disappearance with Xavier and Emma Morvan, shortly before an incident that caused damage at a nearby hotel.

Determined to find answers, Sarah tracks Xavier to his isolated caravan outside town. Inside she discovers troubling signs of drug activity and traces of blood. When Xavier returns unexpectedly, the confrontation turns tense, but he insists Katie left alone after an argument with Emma.

Meanwhile, the investigation uncovers new evidence linking several students to the events of that night. Virginie's questioning of Emma raises further inconsistencies, especially after an item belonging to Katie is discovered hidden among Emma's belongings.

Tensions escalate between Sarah and the Morvan family, whose reactions grow increasingly defensive. The town itself seems divided - some residents sympathetic, others openly hostile to Sarah's relentless questioning.

Then a new development shocks the community: Katie's backpack suddenly appears in a public place connected to an older local tragedy.

Virginie reveals that another teenage girl disappeared in Saint-Michel five years earlier under eerily similar circumstances. As the parallels between the two cases begin to emerge, Sarah realises Katie's disappearance may be part of something far more complicated than anyone first believed.