Harley Quin is an enigma. Even his friend Mr. Satterthwaite is unable to understand how the man seems to appear and disappear almost like a trick of light - and when he does appear it's usually in the sparkle of sunshine, or surrounded by a spectrum of coloured light pouring through a stained glass window. Indeed, he is Harlequin. The only consistent thing about the mysterious Mr. Quin is that his presence is always a harbinger of love .. or death.
(This is a TV Show adaptation of the Mr Quin Stories by Agatha Christie. Each Episode is based the 14 short stories from the Mysterious Mr. Quin collection with later episodes being based on non-Quin stories, altered to insert Quin and Satterthwaite into the story.)