An epidemic of mutant creatures attack unsuspecting victims while in the bathroom causing the mayor to call for federal help to save the city.

I agree with the previous comment. Who uses what power to save the city?

How about something like this:

An ineffectual Mayor must learn to trust his aide to unite his city against a marauding gang of mutant creatures that have plagued the city and are now targeting the Mayor and his staff.

Sounds interesting but I think it needs to clearly state who the protagonist is. Is it the mayor, one of the victims, or a hero that comes to save the city?