There are certainly worse tales to be based on a circus environment.  This game has no tragic backstories to speak of, but there are some evil clowns.  The more we've talked about this game, the more tenuous connections we've made to Batman.  At any rate, follow a competent circus performer as he performs... in the circus.  I suppose there's also the part where he fights off hordes of evil clowns while an audience watches, but, really, that's just the price of admission.