The ghost who has entered Scrooge's bed chamber is undoubtedly Jacob Marley. Scrooge asks what the spirit wants with him; 'a lot' is the reply. Scrooge tries to maintain that Marley is just a figment of his imagination - perhaps caused by indigestion.
But Marley scares him into submission and now the business of his visit may begin...
Marley explains that it is the duty of every person that their spirit should 'walk among their fellow-men'...and that 'if that spirit goes not forth in life, it is condemned to do so after death'. Marley is one such unfortunate: he spent his life amassing his fortune when care for others should have been his business. The dreadful chain he wears he forged, link by link, throughout his life. He can see another chain weighing Scrooge down now.
But Marley has come on a mission of mercy, with an explanation that Scrooge may yet escape a similar fate to Marley if only he will mend his ways. Scrooge is to be haunted by three spirits. The first will come this evening when the clock strikes one.
Marley ends by telling Scrooge to mark what has passed between them. Then he floats out through the open window to join countless other spirits in the sky while Scrooge falls exhausted on his bed and is asleep within an instant.