From the introduction:
It is the Year of Settlement 106, and in the violent years that followed the end of the First Horde War the Colonial Army engaged in a series of bloody battles to keep the hard won lands of the fledgling Nations of Men free from attack. One battle stands above all others for its ferocity in those dark times and this is a small part of that story. In those desperate days the ancient ruin of Clavette's Keep stood upon the east coast of Arborell, south of Callenfrey and at first glance no more than a crumbling pile of broken stone. Beneath its shattered towers however, lay an extensive reach of deep ruins, and within those passages and chambers there resided a determined force of Oera'dim, using the Keep as a base of operations to harry the new settlements of Men. Of great concern to the Colonial Army was how those warriors had made their way so deep into the lands of Men without detection. It was a question that had to be answered. It is your mission to find out.