This is an R-rated splatter fest with a token Jeremy butt shot. If you go expecting anything deep and meaningful, you're going to be sorely disappointed. If you go expecting a fairytale version of Lethal Weapon with a lot more one-liners that are so fucking bad that they're funny as hell, then by all means, sit back and enjoy the ride.
The movie starts with the original Grimm fairytale. Mom tells Dad to dump the kids in the woods. Kids stumble across gingerbread house. Blah, blah, blah...
The credits roll showing H&G growing up to become the most famous witch hunters in Europe. They have some kick-ass, steam-punk weaponry they've developed. They run around in tight leather. And they have a freaking fan club!
But the side effects from their original ordeal left scars. The emotional ones, like the siblings trusting no one but each other. Physical ones, like Hansel's diabetes.
The mayor of Augsberg hires the siblings to track down and kill the witches responsible for a rash of missing children. The sheriff is more than a little pissy about H&G intruding on his territory. Gretel and the sheriff literally butt heads when he tries to drown an innocent woman for being a witch.
The siblings stumble upon the evil witches' real plan, but their efforts are hampered by the sheriff. When he and his men try to rape Gretel in the woods, she's rescued by a supernatural hero named Edward.
Yep, there's a lot of sly pokes at several other movies and some cultural references that make you laugh and then cringe because you laughed. (Namely, the missing children pictures on milk bottles.)
I can't say much more except secrets are discovered, H&G's parents are redeemed, and the movie climaxes at the very same gingerbread house where it all started.