Das doppelte Lottchen (English: Lottie and Lisa) is exactly what I loved to read as a child. The story of the twins Liese and Lotte, who were split up soon after birth when their parents separated. Once the two very different girls realise they are twins at a summer camp, they decide to switch places.
It’s like a modern fairytale. Kästner takes elements of modern life, like parents separating, and weaves them into fairytale elements with secret twins, children’s deception and anguish and joy.
As always, Kästner has a not-so-secret agenda, but in this case it is the least obnoxious, the most human. Also the only one without a transparent self-insert. This book feels deeply like childhood to me, and I like it a lot.
Of Kästner’s novels, The Flying Classroom feels very similar to this one, as does Emil. Of other books, the Jim Button series comes close in the way it shows the world from the perspective of children. For slightly older children, the Young Wizards also shows children struggling with the real world in a good way.