"Mr. David Hume." Reginald Brett, barrister-detective, twisted round in his easy-chair to permit the light to fall clearly on the card handed to him by his man-servant. "What does Mr. David Hume look like, Smith?" he asked. "A gentleman, sir." Well-trained servants never make a mistake when they give such a description of a visitor. Brett was satisfied. "Produce him." Then he examined the card.