I would write a story about batman fighting a villian who is trying to purge that he believes to be the supernatural sickness causing gotham to rot ( ie killing notorious rotten families, destroying landmark thought to be corrupt or built on corrupt land). The story would explore what makes gotham a city that corrupts every one who lives in it and drives them mad (batman, harely, two face, ect) and explore how t he history has caused the city to deteriorate (such as the fact it was founded by a mercenary). The villian is not insane, he is clear headed. We also vet characters like the spectre and phantom stranger and Jason blood, who give insight to the idea that maybe the corruption is supernatural and haunted by the sins of yesterday.