Beneath the Dome is an adventure for the Castles & Crusades game by none other than James M. Ward. The current versions out in game stores and OneBookShelf are a combination of four smaller adventures. It is really like a small campaign or a longer adventure in four parts.
Each section challenges characters of progressively higher levels (1-5, 4-7, 10th and above) and deals with the invasion of a race of giant humanoids, the Amdromodon. Aside: While the new monsters here are interesting enough, I couldn't help but think it might be cooler if instead, I replaced them with Slaadi from the old Fiend Folio. But that was only a thought.
The adventures are interesting and I love the whole "invasion" and corruption vibe. It made it feel a little different than your typical adventure dealing with outer planar creatures. A little fleshing out with some other adventures the Castle Keeper could really make a nice campaign with this. The only thing really missing is a very high level adventure where the PCs go to the plane of the Amdromodons.
There is a lot going on in this adventure(s) and it is a lot of fun really. In addition to the new monsters there are also some new spells.
The book itself is 36 pages.
Now. I hate to be "that guy" but today I am going to be.
If your book needs so much editing that *I* notice it then you have some issues. There is more going on here than the odd typo or comma splice. Some sections are so awkward in their phrasing and the way they were written it really made it difficult to read. I know these complaints have been leveled against Troll Lords before and I have for the most part ignored them. But this book for whatever reason seemed to be really bad. Now the PDF might be updated, I don't know. But the physical copy I have needs a lot of help.
Disclaimer: Links are affiliate links, this module was purchased as part of a Kickstarter add-on package.