The main story is about how Nora and her vampire friend Ollie discover a lich in the kitchen making dough zombies. They try to take care of it themselves before Uncle Barnaby gets back. Despite their best efforts, though, they're unsuccessful and require Barnaby's assistance when he finally returns with some cheesecake.
Orchard is clearly attempting to straddle the line between a cute/clever kids' story and something ghastly/spooky. And he does a good job of that. It's not a slap-stick comedy like Beetlejuice, nor is it quite as emotionally dark and brooding as Nightmare Before Christmas. It's visually pretty dark, but with a kind of soft veneer over it. It floats in a nice middle-ground and seems like would be just scary enough for kids without freaking them out too much. I want to make comparisons to things like Death Jr. and The Grim Adventures of Billy & Mandy but that's not really where this is coming from; it has some lighthearted moments, certainly, but it's not really played for laughs. My best analogy might be some of those old fairy tales before the 20th century sanitized them.
Orchard notes in the introduction that he's had Marrowbones rolling around in his head for a while now, and I think it shows. He's got a very clear indication of what he's doing with it, and obviously has mapped out quite a lot more than what's shown. Plenty of details to absorb.
The one complaint I might lodge against what I've seen so far is that, before the main story, there's seven pages of backstory exposition. It certainly shows the depth with which Orchard has thought this through, but I think that could either have been shortened considerably or been made a little more engaging instead of having everything relayed in the past tense by a skeletal narrator. Because of these first pages, I have to admit being a little concerned heading into the main story, though, fortunately, the storytelling in the latter is much more fluid and doesn't rely so heavily on straight exposition.
Beginning tomorrow, Orchard will be selling the 46-page book as a digital download. You can read more about it (and probably get a copy once he makes it live) on his blog.