Zoé and Sammy try to crack the code to open the secret door, while Antoine tracks down the stranger Éloi saw. Mathilde and Éloi, convinced she can help them, try to approach her, but the stranger's suspicion complicates everything.

Zoe and Sammy delve into a disturbing tunnel. Meanwhile, Charlotte and Louna discover a suspicious shelter in the forest, which reignites doubts about Louna's past. Meanwhile, Charlotte questions her feelings for Billi.