Holmes has been called to the dining room where a guest has been found dead, slumped over his soup, wine glass still in his hand. Holmes detects the familiar smell of arsenic poisoning straight away. A witness has been found, Francis Morgan, who says he saw someone slip a white powder into the glass.

Holmes: So you saw the poisoner slip the poison into the glass?

Francis: Yeah. Just 'cos I wear glasses it don't mean I'm blind does it.

Holmes: It certainly doesn't. Now tell me my fine fellow, what did the poisoner look like?

Francis: Well I didn't see much 'cos he was wearing a hoodie and sun glasses. Suspicious eh? And he had one of those old fashioned moustaches. Yeah, in fact he must have been pretty old with that moustache and the way he walked bent over like an old man. Yeah, really old. Definitely over 50 he was.

Holmes: Really? How intriguing. Well thank young sir. Your evidence has been most illuminating. I think we can find the poisoner now.

Watson: Bless me Holmes! How is that possible?

Holmes: With a database Watson, everything is elementary.