During my time playing PnP D&D we played just about every module going including my own but the one that has the fondest memory is the GDQ series. It is a story that begins fairly suddenly with news of Hill Giants invading the land of men. You are recruited to halt the attacks but are warned that the Giants are under a superior commander who seems too intelligent to be a Hill Giant himself, you must follow any leads in order to find who this Warmaster is(G1). Well, it seems that the Frost giants(G2) are behind it until you destroy them and discover that they too are under orders, from the mighty Fire Giants(G3). It is in the depths of the Fire Giant Kings Halls that you find that in fact ALL the Giants have been mere pawns for a greater intelligence - the Drow.