The party is recruited by an innkeeper to recover a flower from a nearby mansion. He is an alchemist and he is running short on his supply of the Midnight Violet.
Town rumors warn the party to stay away. But, that's unlikely given that your heros are mighty and brave.
While exploring the mansion, the adventurers will learn the story of the family that once lived there and what caused their demise. That is... if they live that long.
For 4th - 6th level characters.