If the PC:s, after defeating the bandits, find the secret door in the leader's room and decide to go down there (reaching the closet to the north of room 14) instead of taking the stairs (to room 11) and go north from that closet, they'll bypass the cell block and meet a band of ornery bugbears instead. More on those in a few posts, but as it is this room is likely to be the third combat encounter.
What we have here is an encounter with the ogre Lubash and metric buttloads of zombies. If the PC:s get hold of the evil looking cloaks from room 12 and wear them, Lubash will invite them to his lair to keep them safe from the zombies (because he'll think they work for the evil cult running the show on the lower levels). The bandit leader is a good opportunity to drop this factoid, but as written, expect a fight.
Lubash - a level 8 skirmisher - is a pretty good match for level 4 PC:s. However, if they enter his room from the north (like my players did), the zombies will arrive after he's dead and get slowly slaughtered as the PC:s can bottleneck them in the two rooms leading there. It's a decent fight, and I'd say the players deserve the easy ending if they bypass the zombies by taking the back door, so I have no changes to suggest.
Room 14 is Lubash's larder, which holds some prisoners (including any replacement PC:s you want to put there) The group has now taken on three fights of varying difficulty, become responsible for a few prisoners, and possibly found out that there is a nasty cult afoot in the Moathouse. This is an excellent opportunity for them to report back to Hommlet. More on that in the next post.
Finally, a peevee. There are two ways to progress. Both are secret - the passage to the north and the secret door in the pillar in room 13. The DC:s for spotting either are also quite high. On the other hand, if everyone searches, someone will probably succeed, so it's probably OK. If the PC:s are totally stumped, have the ghouls in the room to the east attack (leaving the secret pillar door open).