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Madness of the Rat King
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Madness of the Rat King

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A self-contained weird and wonderful adventure! Mutant rats, beautiful maps, and strange loot!

Madness of the Rat King is an 5th edition adventure for a party of low-level characters. You can start a new adventure with Madness of the Rat King, insert it into an ongoing campaign, or run it alongside the Fiery Grog Tavern supplement!

This romp through a mad alchemist’s lair can be run from start to finish in about one or two gaming sessions. The module requires little planning beforehand aside from reading it over. Everything you need to run the game, from maps to monster stats, is contained within these pages. The adventure has enough encounters and challenges to advance the party by one level by the end of it.

This adventure package includes:

  • A self-contained adventure that will entertain a group for one or two sessions
  • Plenty of hooks to lead the party into the adventure and even more plot lines to continue the story after this adventure is complete
  • Gorgeous high resolution maps of the entire dungeon for print or online play made by Ross McConnell from
  • 11 brand new monsters
  • 8 brand new magic items
 Customers Who Bought this Title also Purchased
Reviews (13)
Discussions (5)
Customer avatar
Drown B December 18, 2018 6:29 am UTC
Hey, I have a question about the gridded versions of the maps. When I go to print them out, it seems to layer the hexagonal and square grids over each other. I really only want the square grid, so is there any way for me to just get the one grid? When I view it in the browser with a pdf reader, it seems to appear with only the square grid.
Customer avatar
Charles V October 16, 2017 6:14 pm UTC
There seems to be a problem when i try to download most of the files, telling me that "the file was found, but no job related to the file was recorded." This happens with 11 files.
Customer avatar
Tomer A August 23, 2018 4:49 pm UTC
Sorry for the delayed response, Charles. I hope you ended up getting the files in the end!
Customer avatar
Lydia S November 02, 2018 1:02 am UTC
I just purchased this and can't download any of the files at all.
Customer avatar
Kristin F January 08, 2017 10:24 am UTC
Ran this for my group. As I DM I found it easy to run and it didn't require huge amounts of preparation for me. I play with a family with kids (aged 15, 13 and 10): they all thought it was great fun, and so did we parents!
Customer avatar
Tomer A June 04, 2017 4:24 pm UTC
Thanks for choosing this adventure, Kristin! I'm glad you and your family enjoyed it!
Customer avatar
Alastair M May 25, 2016 9:34 pm UTC
There may be a problem with the Cavern_Full.jpg file, as I get only an "Invalid File" notice when I try to view it. I've downloaded it twice now, with the same result each time. Everything else opened fine!
Customer avatar
Tomer A May 25, 2016 9:54 pm UTC
That's odd. I downloaded the file and it's opening fine for me. I can email you the map directly if the problem persists.
Customer avatar
Alastair M May 26, 2016 8:56 pm UTC
OK, many thanks for the updates.

The problem with the Cavern_Full.jpg still persists, unfortunately, though again, all the fresh downloads - PDFs and JPEGs - were otherwise fine. 45 MB is certainly a moderately large file, but I've downloaded plenty of others from the OneBookShelf sites before that are several times greater in size without problems. Plus the 35 MB Cavern_Full_label.jpg downloaded first time with no problems.

What I noticed this time, as with the second attempt previously (when I was paying closer attention), is that the file download gets to about 3/4 to 4/5 of the way through and then suddenly slows down markedly, before speeding up again. That can be an indication there's a problem with the file, or the download system. I have a suspicion that as a publisher, your file download from the OBS sites won't be quite the same as that for a purchaser, which may be why you're not getting the problem.

You may be able to resolve this by removing the current version...See more
Customer avatar
Tomer A May 27, 2016 12:03 am UTC
Thanks for keeping me updated, Alastair.

The latest update added the missing map, and I also deleted / reuploaded the Cavern_Full.jpg . I've also added Cavern_Full_Smaller.jpg , a smaller (but still big) version of the problem map. Hopefully that fixes the issue, otherwise I'll get in touch with technical support.
Customer avatar
Alastair M May 27, 2016 2:12 pm UTC
Sorry, Tomer. This is really irritating, but although the Cavern_Full.jpg image downloaded without any obvious delays this time, it still just comes up with "Invalid Image" when I try to view it. Cavern_Full_Smaller.jpg was fine the first time I tried it yesterday, and the PDFs and the other JPEGs are fine too, just not this one image for some reason.

Might indeed be worth contacting tech support, because this isn't the kind of problem you need if you're planning more such publications in future.
Customer avatar
Tomer A May 28, 2016 11:49 pm UTC
I'm sorry that this issue still persists, Alastair. I've contacted tech support last night and hopefully will have a response monday.

Until then, you (and anyone else) can reach me at and I will send you the file directly.
Customer avatar
Tomer A May 31, 2016 11:05 pm UTC
Hey Alastair,

Here is the exact response I've received from tech support:

"We can open the Cavern_Full.jpg without an issue. My suggestion would to direct the Customer to Customer Service as it might be the program they're using to view it. Customer Service will work with the customer on getting it open: "

Hopefully customer support will do a better job than I in fixing the problem.
Customer avatar
Alastair M June 01, 2016 12:52 am UTC
Lucky them! Doesn't matter what program I try it with, all I get is zero - for all intents and purposes, the downloaded file doesn't exist in any kind of readable form. Given this is the only JPEG from this set of files I can't open - indeed, it's the only JPEG I've ever encountered that I can't open at all - I can't see how this can possibly be an issue for my computer systems.

I strongly suspect the problem is being created somewhere in the OBS file download system in fact, corrupting the file during download, in essence, and that tech support haven't even considered this.

Bottom line is not to worry further about it, I'd suggest, given I can access the PDF and lower resolution version of Cavern_Full. It may be something to be aware of in future though, given KM Y also seemed to be having an issue in opening the Cavern_Full file. If it is a file-size issue for the OBS download system at the root, it may be best to make sure there's a lower-res version as well, just to be sure!
Customer avatar
Tomer A June 02, 2016 7:35 pm UTC
I did one last re-upload of Cavern_Full, lowering the resolution and size a little bit (25 MB from 46 MB) but still larger than Cavern_Full_Smaller (2 MB) and should be more than sufficient for covering any gaming surface. If that fixes it then great, if not then I've run out of ideas.

For anyone reading this and still having issues opening feel free to email me at and I will email you the file directly.
Customer avatar
Alastair M June 05, 2016 6:43 pm UTC
Thanks Tomer. No problems with this version of Cavern_Full certainly, though it was unusually slow to load in my normal viewer - slower than I'd ordinarily have expected for something "only" 25 MB in size. Maybe best to stick with 300 dpi game-tile-sized artwork in future?
Customer avatar
KM Y May 25, 2016 8:00 pm UTC

First of all, great adventure and presentation. I'm looking at the individual area jpg/pdf files and I can't seem to find 2 areas, the torture room and the chamber where the warhammer is. Are these files missing?
Customer avatar
Tomer A May 25, 2016 9:56 pm UTC
The torture room is labelled "CavernCorral.jpg" which I should probably change. The map containing the chamber with the warhammer was missing, sorry! I've now added the jpg and pdf files for it.
Customer avatar
KM Y May 26, 2016 3:12 pm UTC
The "CavernCorral.jpg" only has the cage area and not the torture room. With the update and the inclusion of the waterfall, there are 7 individual area files, which seems odd as there should be an even number for a rectangular map.

I also seem to be having the same issue as Alastair M with the Full map.
Customer avatar
Tomer A May 26, 2016 7:29 pm UTC
I added the missing map, CavernTortureChamber. Also I added a new map, a smaller (but still huge) CavernFull.
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File Last Updated:
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Maniac Brews
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