Koba and Baraka visit Uncle Busisa in Big Number, a city where street names are written in numerals. However, because Koba and Baraka don't know how to read big numbers, they get off at a different stop than they were supposed to and end up getting lost. They meet Mama Ndege and Ngedere, who are on their way to distribute corn to rats on Rat Street. Koba and Baraka join them, and while there, they learn to count big numbers and eventually find their way home.