This is a story about the boy Bertil who feels very lonely because his sister has just died and his parents have to go to work. Then one day something happens, because from underneath Bertil’s bed, a little boy called Nils appears. He is only 20cm tall and invites Bertil to his home in the basement. It only takes one magic word to shrink Bertil to the same size as Nils and together they set out to beat the scary rat but eventually they have to be saved by Auntie Hulda’s cat.