It's the middle of the night at the Anne Frank House in Amsterdam, and a magnificent thunderbolt has just struck the building and shattered the protective glass case in which the most famous diary in history is displayed. Magically, Anne's imaginary friend, Kitty, comes to life. At first Kitty doesn't know that seventy-five years have passed, and she has no clue as to why Anne is not in the house or what has become of the seven other inhabitants of the Secret Annex.

When Kitty learns that Anne and her beloved sister Margot have died in the war, she decides to run away from the house, and follow the path of the sisters all the way to where they met their fatal end. Kitty, who soon realizes that she cannot exist without Anne, decides to steal the diary from the museum and starts her journey.

Kitty recounts the complete story of Anne Frank's life, family, and diary from her own unique perspective. In the present day Kitty's adventures bring her in contact with the refugee crisis in Europe, from which she discovers the true meaning of Anne Frank's legacy.