AMY AND NATI: The secret of the Eiffel Tower

The secret of the Eiffel Tower is the 3rd picture book's series "Amt and nati".
For the 5-9 years old.

It is by a cold winter day, as everybody stays warm, that Amy and Nati decided to visit the Eiffel Tower. Their parents bothered by their insistence, finally gave in.
What could stop them? A snow storm? a car accident? The ticket offices closed?
Certainly not...