I've been looking over my old modules, I always loved this The Night Below Boxed Set campaign but never got to run it. I only skimmed it, because we used to co-dm and I wasn't sure which of us would run it.
I have it in "kinda" PDF form after scanning long time back. But, I'd like to BUY it for a better professional scan.
If anyone else likes this one - maybe hop to DMsGuild and hit "Contact" at bottom left side (red) button and ask them to look into getting this one done by WotC :)
(FYI... I would SOOOO love to get this into FG, not a pro at 5e, so not sure how well I'd "convert" it but hey... ;) )