Someone in the misty, wooded Moonshae Isles needs hundreds of brand-new swords taken under guard from Sword Coast smiths to a certain place on the Isles. The swords are needed so badly, and their safe arrival is considered so unlikely, that someone is willing to pay adventurers a lot of gold - someone fairly important. Adventurers foolish enough to take assignments too find themselves embroiled in a dark and mysterious struggle against evil that will take them into sacred groves, crumbling castles, and through ancient magical gates to the halls of the High King - and beyond. This sourcebook contains background lore on the Moonshaes, a DM's delight of new monsters, magic items, and spells usable in any AD&D campaign and enough adventure ideas to keep the most energetic player characters seeking their fortunes in the Moonshaes for years to come.