From the introduction:
Sir William was an old aristocrat who loved and supported wizardry through his life. Each year for his own birthday, he organized a great convention at his manor, where lovers of magic – regardless of race, religion, or magic affiliation – were invited from all over the region to showcase their newly-learned spells and powers to the community. After William’s recent death due to old age, the wizard community called everyone together for one last dazzling night to pay respect to their old benefactor. The PCs were possibly invited, or maybe stumbled upon the manor, which sits on top of a hill, and is surrounded by a beautiful vineyard. After meeting with many different folks and drinking various spirits of questionable origin, the world suddenly went black...