The Six Napoleons
'Now you can see that the story becomes more understandable. The other fellow is probably also Italian, and he is probably also a member of the Mafia. Maybe he has broken the rules in some way. Pietro is told to go after him. Probably the photograph we found in his pocket is a picture of this man, so that he would not knife the wrong person. So he followed the fellow, he saw him enter a house, he waited outside for him. Then there was a fight and he was killed instead of the person he meant to kill. How is that, Mr. Sherlock Holmes?'