Framed in the doorway of Poirot's bedroom stood an uninvited guest,
coated from head to foot in dust. The man's gaunt face stared for a
moment, then he swayed and fell. Who was he? Was he suffering from shock
or just exhaustion? Above all, what was the significance of the figure
4, scribbled over and over again on a sheet of paper? We follow Hercule
Poirot as he finds himself plunged into a world of international
intrigue, risking his life to uncover the truth about 'Number Four'.