It is a cold, grey day at Number 49 and everyone is in a bad mood. It is too cold for the children to be outdoors and they are b-o-r-e-d … that is, until they hear a mysterious voice coming from the fireplace.  Who can it be? Is it a burglar? The Big Bad Wolf? Or is it Father Christmas? The children soon learn that the mysterious voice is that of Percy Potter the Chimney Sweep, who warms their home and brightens their day with his charm.