Margot Robbie stars in a scene from the movie "Harley Quinn: Birds of Prey". Photo: Warner Bros/CNS. By John Mulderig The DC Comics adaptation Harley Quinn: Birds of Prey (Warner Bros) is presumably intended as a tart treat. Instead, it comes across as a sour exercise in random mayhem. Margot Robbie plays Quinn, the psychiatrist who fell for Batman's nemesis, the Joker, while treating...