What is your opinion on this plot i've put together for a novel?

I would definitely stay away from that plot. I'm a writer as well and I hail from Michigan. That kind of plot would make it harder for the audience to attach to the main character (who I assume will be the demented man). I think it is way too far out of the box for most people. Rape and murdering children is not something more people want to read about. I would avoid this plot like the plague. You could try doing this as sort of a Hannibal Lecter, reflecting over it from his prison cell while he explains what happened to a police officer or make him a serial killer who didn't just kill and rape his daughter but other people too. If you dwell too much on the fact it was his daughter I think you'll frighten people off in the worst of ways. If you plan on getting this published and it involves incest rape and murder I don't think you'd have a chance to get it published. Just a few thoughts.