From the back of the book:
Thousands of miles from the city of Rome, across the roiling, icy waters of the western sea, lies the edge of the empire. Here the province of Britannia stands, at the very end of the known world! To the north, beyond a great fortified wall, lies the great and terrible lands of Caledonia, home to savage painted barbarians. Further west, across a narrow stretch of ocean, lies the green and mysterious lands of Hibernia. Throughout all these lands, from the civilized urban centers of the south to the wild war-torn regions of the north, over the wall or across the sea, peril lurks in every shadow. In ancient forests and atop lonely mountains, beneath the surface of misty lakes and treacherous bogs, or masquerading as our neighbors, the Great Old Ones rise, freed from the bonds placed over them by the now shattered druidic order. But they are not the only danger in this far off land, for it is said that a race of selfish, meddling beings crosses the veil between worlds, to pursue their own agenda in our world of iron, and they are not our friends.