From publisher blurb:
A Threat In Grassfel is the first adventure module in the upcoming Heroes Of Grassfel campaign. It not only highlights the areas in the Kingdom of Karak which was presented in The Land Of Mithgarthr, it further fleshes the setting out and helps to give a "feel" for the area and the people who inhabit it.
The adventure itself revolves around the party finding a set of magical thieves tools before the minions of the looming threat of Morcar are able to get thier green hands on it. The party will also encounter a ratten, which is a creature detailed in the Mithgarthr setting book.
However, for GMs looking for a fun, quick dungeon romp for first level characters, A Threat In Grassfel is easily plopped into whatever setting you like.