Pia and Jonas think the idea of the children's apartment is absolutely great! If their estranged parents have to separate, they should each find a new place to live – the siblings will stay where they are. From now on, their mother Juliane will live with them for a week, followed by their father Linus the next week – always alternating. For a while, this arrangement actually works quite well, but ever since Juliane got a new boyfriend and Linus even has a new family, nothing seems to be going right anymore! There are problems at every turn in the children's apartment. Meanwhile, Pia has much more important things to do, as she and her friends are offering clueless tourists city tours. And 'Berlin for Strong Nerves' is currently a huge hit! Just when a new landlord shows up in the Reuterkiez along with a lawyer, the siblings also have to meet Fred, the new guy, which complicates things even further.