The characters are well-defined. Most of the major plot points are clear. New points are emerging, and little details that tie everything together are popping up pleasantly proffering practical and promising plot points—crap, I already used “plot points”. This is why you must resist the siren song of alliteration, Sean Penn!
The only thing that’s really lacking is the sense of urgency. I mean, on the one hand, we do have a ratcheting of tension—really, borrowed from Stoker, who does it just by the power of assertion—but it starts about half-way through, and we want a little more than “because we say so”.
The original has a double-inciting event: Adam Salton Arrives. Also, Edgar Caswall arrives. Note that neither of these arrivals is The White Worm. So how do they incite? One of the flaws with the original, in this regard, is precisely that it puts Caswall in the center of the activity—all well and good if one didn’t have a book named Lair of the White Worm—and the original compounds this by not actually giving us a white worm till about 2/3rds of the way through!
Now, I can rationalize Edgar being the inciting event and support it, but this makes our Worm more passive than it behooves a GADS* to be. One of the great things about Dracula is how ahead of the game the Count always seems to be. Our Lady of the White Worm (what does he even mean by that?) should be no less formidable, and be operating under the radar until our heroes figure things out.