American writer Winifred Rudge is in London to research a novel linking Jack the Ripper to the house in Hampstead where her own great-great-grandfather, rumoured to be the model for Ebenezer Scrooge, lived. Instead she uncovers the mysterious disappearance of her cousin, John Comestor, the latest resident of the family house. Moreover, something is making an infernal racket inside the chimney, and soon there are other bizarre manifestations of some unseen force.