I'm under the distinct impression that Forces From Beyond (or Bayonne, if you're from Jersey) is the last of Simon R. Green's Ghost Finder novels. It's actually a satisfying way to end it, explaining one whole heck of a lot of what's been going on over 6 novels and finally revealing what happened during JC's confrontation with Fenrir Tenebre back in book 1.
In this, we start with a haunted hotel room that confronts people staying inside with their own life purpose or lack thereof. After providing some team building for the Finders, we then move to a Carnacki Institute convention where we find out Lattimer (who runs the Institute) has decided to team up our heroes with their counterparts in The Crowley Project, since the physical location of The Flesh Undying has been found in the Atlantic Ocean.
The death of all the convention attendees, Lattimer being replaced as head, and a confrontation with the Faust winds us up on a boat floating over the Flesh with the overall plan being dropping JC, Melody, and Happy down in the depths in a bathysphere.
Anyway, there are quite a few revelations along the way, as Green does his darndest to wrap up multiple plot lines.
As I keep saying, if you've read any of his other work, you have an idea what you're in for when you crack open the first page. But he does so with skill and panache.