Because of dark fir trees and green meadows in the sunshine: When Heidi arrives at her new home in Frankfurt, a plainly papered wall blocks any view of the outside. And the mountains, where she recently lived carefree with Peter the goat and her grandpa, Almöhi, are far away.

How the story continues is known: from the books by Johanna Spyri, from Heidi series and Heidi films. At the Salzburger Landestheater you can see since Friday that …