From the Publisher:
The Underhill Court has come for a time, and if you dare, you might find its hidden door. Within its ballroom sits a cold queen, a relentless king, a jester so riddled and horrible his only joy is to cause others to suffer. There within the chambers of the Court revel the ageless sidhe, the Tuatha de Danann: childless, timeless, never tiring of their pursuit of pleasure. Will you be their honored guest, or the night's entertainment?
The Underhill Court can be dropped into any d20 fantasy campaign or be used as a stand-alone adventure. The book contains new monsters, magic items, intriguing npc's and the infamous fighting pit, as well as a bonus book of maps drawn to-scale on a 1-inch grid for tabletop gaming.