Two young girls discover a chest full of period costumes but it is haunted by the Spirit of the Great Beaver. He sends them back to the beginning of New France and teaches them about the books and occupations of the colonists.

« MIMI : Can you tell me where we are? / LÉA : In my grandmother's attic. / MIMI : Léa, wake up! We're not in an attic anymore. / LÉA : I know, but this is all so incredible. / MIMI : I know, but that land in front of us is Montreal when it was founded. It must be the ghost in the attic who brought us here, to prove that he really exists. »