A ghost town appears in a steampunky alternate Old West. (The steampunkiness of it all is only hinted at, however. The book I missed must have covered that stuff.) Pilgrims gather, having been told -- mysteriously -- that this town will offer tourist trips to the afterlife, one day only.
The offer turns out to be something of a cheat, of course. The story primarily follows a retired preacher-or-something and a nameless gunslinger-in-black, who sneak into Wormwood. (The gunslinger knows a trick or two, and has business inside.) They wind up doing the full tour of Hell, accumulating a crowd of sidekicks as they go. We occasionally jump back to the frustrated crowd lined up outside.
Hell has great scenery; the Old-Weird-West ambience is a great fit. (Better than Los Angeles, I have to say.) But -- as is so often the case in these Milton riffs -- the author doesn't have much to add to the story of Lucifer-vs-God. Or civil-war-in-Hell, which is even more common in recent fantasy. Calling Hell "the Dominion of Circles" (c.f. Dante) doesn't really shake things up. As for the closing gag, well, DeChancie did it decades ago as I recall.
Also, I've had enough succubuses for a while, thanks.
In addition to discovering an unread prequel, I discover that I read an (unrelated) earlier novel by the same author. The World House had good scenery, but an unengaging narrative and annoying characters. This series has good scenery and engaging narrative and (some) fun characters, but it's thematically not going anywhere. I mean, maybe the concluding book is full of electrifying insight, but nothing leads me to think so. Thus, I figure I should skip it and try the author's next series. He's improving but not there yet, at least for me.