SUPERMAN RETURNS director Bryan Singer plans to make a completely different follow-up to the superhero blockbuster - a biopic about homosexual San Francisco supervisor and gay rights activist HARVEY MILK. THE MAYOR OF CASTRO STREET will portray Milk's story as the first openly-gay elected official in a major US city. In 1978, Milk and San Francisco Mayor GEORGE MOSCONE were assassinated within minutes of each other. Both men were shot several times by DAN WHITE, a former policeman and member of the San Francisco Board Of Supervisors. Singer says, "It's a project that has fascinated me ever since I saw a documentary about it. "(Milk's) an extraordinary character, as a person in history. We're developing a story based on him that will probably centre around the latter period of his life, leading up to his assassination. "He is one of the great role models of our contemporary society that, unfortunately, a lot of people don't know about."