Idea for a movie script?

I want to make a serious movie over the summer, but don't have anyone with good ideas for a script. So any ideas of where to start would be appreciated. I'm not asking for all the details or actual writing, just the synopsis. Genre-wise I don't care all that much, though I'd prefer something that's not heavily romantic and doesn't have any necessary effects or settings that are unattainable for someone without bundles of cash.