What is the plot of A Christmas Carol?

On Christmas Eve, Ebenezer Scrooge is visited by a four ghosts, starting with his old business partner, Jacob Marley. The three spirits which follow, the Ghosts of Christmas Past, Christmas Present and Christmas Yet to Come, show Scrooge how his mean behaviour has affected those around him. At the end of the story he is relieved to discover that there is still time for him to change and we see him transformed into a generous and kind-hearted human being.