One day before Christmas, on December 23, the Schmidt family moves into their new apartment in a Berlin high-rise; until then, they lived in tranquil Birkenwalde. Little Sebastian fears that Santa Claus doesn't know about their move and therefore won't be able to bring him his presents. Even if he knows where Bastel and his parents now live, he might not be able to find him because there are several families in this large building with the name Schmidt.