After defeating the False Burne and rescuing the real Burne, the PCs camped outside the ruins of the moathouse. During the night, they heard a variety of horrid noises from the place. The screams of kenku and the roar of strange creatures echoed from the moathouse's halls.
The next morning, a cursory investigation of the False Burne's chambers turned up nothing of note, the adventurers decided that withdrawing back to Hommlett was their best option.
As the PCs made their way past the moathouse along the faint track back to Hommlett, they saw the corpses of the kenku they defeated when they first stormed the place rise and shamble into the main building. Their curiosity piqued, the PCs approached the ruins once more. As they entered the courtyard, a dark cloud appeared above them and cast the moathouse into a gloomy darkness.
The PCs entered the moathouse, only to come under attack by kenku animated as wights, ghouls, and strange, boneless horrors. An undead cleric of Iuz led these creatures against the PCs. After a tough battle, the PCs defeated the undead creatures. However, the dark cloud stil hovers above them, and from the dungeons beneath the moathouse they can hear the shrill cries and echoing moans of undead creatures.
Somehow, a horrid evil has awoken within the moathouse.