From the introduction:
Fury of Thringalesh is the second part of a three part series set in the world of Terra Minor. It is strongly recommended that your players complete part one, False Promises before beginning this adventure. The GM can skip part one and start this adventure, Fury of Thringalesh but will need to provide the players with considerable background details (see Adventure Background and Starting the Adventure for the background information).
This B/X adventure is designed for three to five adventurers ranging in level from 2nd to 4th. The GM is welcome to add or remove enemies to change the difficulty level for his or her group if necessary. The adventurer count is merely a recommended guideline; the GM can run this adventure with more or less players with minor modifications.