From the publishers blurb:
The mighty wizard, Septor the Green, has disappeared, but the ruins of his castle remains. This once proud landmark has become a haven of evil. Few adventures have been brave enough to explore the ruins and those few, have little to show for their efforts. Still rumors of the wizard’s treasure persist, as do rumors of a dark cult lurking in ruin’s dungeons. Are you courageous enough to brave the ruins and battle the creatures that call it home? If so, maybe you can discover the wizard’s treasure. The Castle of Septor is an Old School Revival module designed for 4th to 12th level characters, and intended to be placed into an existing campaign.