The Grim Joker — Gerald Verner

Mr. Hamilton Lorne is amused to receive a card with the grotesque picture of a fool, complete with cap and bells, one finger pointing at the holder. He and Superintendent Budd of Scotland Yard laugh at the threatening limerick scrawled across the back, assuming it is a feeble practical joke, and drop the card into a waste-paper basket. But no one is laughing when the following morning Mr. Lorne is found dead, stabbed through the heart - the first in a series of sadistic murders perpetrated by the elusive Grim Joker.