It had been a typical New Year's Eve party. But as midnight approaches, Mr. Satterthwaite - a keen observer of human nature - senses that the real drama of the evening is yet to unfold. And so it proves when a mysterious stranger knocks on the door. Who is this Mr. Quin? Mr. Satterthwaite's new friend is an enigma. He seems to appear and disappear almost like a trick of the light. In fact, the only consistent thing about him is that his presence is always an omen - sometimes good, but sometimes deadly....