From the front page:
The monks of the Monastery of the Yellow Rose have long cloistered themselves in their home atop the Earthspur Mountains, practicing their strange lifestyle which is rumored to give them longevity. Now, their dietary restrictions and practices of breath control have become the fashion amongst the well-to-do of Mulmaster. But when a few of these lay practitioners start dropping dead from suffocation and starvation, others start to question the validity of the monks’ claims. Is this simply a deadly ignorance, or is there a fell wind blowing through the rich and powerful of Mulmaster?
No level range given on front page. Introduction section on p. 2 says, "This adventure is designed for three to seven 1st-4th level characters, and is optimized for five 3rd-level characters."