Well the party continues into the keep trying to make it to the forge. Along the way they discover some details. The keep is keeping itself up by using the power over death with keeping some of the former keepers around by the undeath. The keep has no Helm to get it up and flying. The demon prince orcus has some interest in the keep. There has been vampires involed also drow vampires. So it will be a very hard fight to clean the keep out and take control.
The next level is the engenering level right below the comand deck. If they can get the internal defenses online the keep can rid itself of the intruders. On the command deck is also a teleport circle once that level is secure the rest of the keep can be sealed and dealt with as needed.