You may find it useful to refer to the map of Tymark's keep for this section.
The party regrouped and reported their findings to Derdriu, who found the situation basically confusing. She recognized the name "Shatru" as belonging to a peasant warrior who had once worked for the Shade Lord. She also noticed that one of Beeel's trollhound bites appeared to be gangrenous.
Derdriu asked the party to meet with one of the guards, who'd seen someone he thought was suspicious a day or two earlier. The person seemed like a short and muscular peasant, did "this weird dance in the mornings for hours on end", had dragon tattoos on his back that looked like they were moving over his muscles (Frankel was hoping for some other sort of tattoo but wouldn't say what), was popular with the ladies, was asking about the party (particularly Beeel), said that the keep was going to be attacked by demiliths some night in the near future (Frankel fixated on demiliches and wondered how they got around to attack things, while Meldrim jumped to demiloths and wished he knew more about them), and wanted to know about the keep's defenses (making the demilith attack story somewhat suspect).
Meldrim also paid a visit to his usual contact. Her bandit friends had asked her to meet them outside the keep that evening; this wasn't particularly unusual, but this time they wanted her to stay with them the whole night. Meldrim said he was worried about her getting trapped outside if her escapade didn't go well, and the young lady confessed that she had a way to sneak in and out. Some time ago, Tymark's dogs had dug through the wall of the goat pen. Harthika had filled in the tunnel, but it was partially open again; while an armed and armored person couldn't fit through a small unarmored person or a child could make it.
Meldrim relayed his findings back to Harthika and the party and considered trailing his contact to try learning something from their meeting, but with the defenders' ranks already depleted, he didn't think he could be spared if the attack came while he was gone. Ahlonna rigged an alarm at the tunnel's opening and moved Brand and Meldrim's horse into Tymark's house (figuring the bandits would steal them if they were left in the stables), Harthika set up a bunch of torches to illuminate key locations (the circles on this updated map, which also shows the tunnel opening into the goat pen), Meldrim was issued a slow poison potion from party supplies and a healing potion from Zenig (to replace the one he gave Beeel, at least until Zenig gets off the weekly table), the party set up guard posts inside each gate and outside the temple, and everyone settled in for the night.
Ahlonna's alarm was tripped in the wee hours; when Meldrim was guarding the west gate, Lorcan and one of the guards were on the east gate, Frankel was at the Belhor shrine, and Ahlonna and Zenig were asleep in Tymark's house. Meldrim snuck out to the goat pen to intercept whoever had come through, entered combat with a goblin, and bellowed an alarm. Ahlonna woke up and moved to cover Meldrim's post at the west gate (and had Zenig lock the keep door behind her), Meldrim chased the goblin as it ran out of the pen and among the squatters' huts, another goblin emerged from the tunnel and started shooting arrows at Meldrim, and Frankel barreled into the area hoping to settle his grudge against Korda. Meldrim and Frankel both downed their goblins, Ahlonna spotted a dozen bandits outside the west gate, a group of people claiming to be Circular City folk under attack appeared at the east gate asking to be let in, the local guard blew his horn, and giant wasps flew in over the east gate and the goat pens, attacking Lorcan and Frankel.
Meldrim moved to the east gate, planning to climb one of the ladders and esense the people outside. Ahlonna tried to draw Lorcan's attention to the west gate but failed. The local guard climbed the other east gate ladder, took a peek over the wall, and was promptly plugged with a few arrows, removing any uncertainty about who was outside. Lorcan decided it was time for a fireball.
Meldrim judged that the east gate would hold for another few minutes, while the bandits would need at most another round to enlarge the breach on the west side. He had the guard take over trying to shoot down the wasp, directed Lorcan to a more central location to try fireballing the western bandit squad (since Ahlonna's attempts to bring him closer to the west gate had been ineffective, he was out of spell range where he stood), and moved to the shrine to try picking off the bandits there.
Lorcan finally got his fireball off and used it on the flying mage, who lost the spell she was in the middle of casting (and revealed that she had a stoneskin). A goblin archer tried to finish Frankel off but failed, and he managed to quaff a healing potion to put a little more distance between himself and the afterlife. Two of the guards took out the goblin on their way to the west gate. Four halbardiers made it through the stinking cloud and started trying to break down the door to Tymark's place; inside, Zenig started stacking firewood in front of said door. Meldrim and Ahlonna cleared away the remaining bandits near the temple, and Harthika went into total parry mode and tried to ride out the phantasmal killer's duration.
Lorcan continued to chip away at the flying caster with magic missiles, and Beeel flew down out of nowhere and got a chokehold on her. He noticed that the caster was wearing a mask over her entire head, and something looked like a face on the back of it, but he made a save and wasn't particularly frightened by it. The archers outside the west gate started firing at Beeel and the caster (none other than Mask, the Face of Chaos), who dimdoored away before Beeel could get through her remaining stoneskins.
(Derdriu's plan all along had been to leave the keep undermanned and draw the bandit attack, so she, Beeel, and Thorongil had headed off to watch on the bandit encampment Beeel and Co. had found the night before last. They recaptured Vajan, who was also there trying to spy on the bandits; she'd heard there was going to be some excitement that night and was investigating how to profit from it. Vajan and Biggs had gotten captured by Tiger [who'd kicked her out of his band sometime earlier] after they'd left the party at the grove; they got separated during the escape, and Biggs had the map [because Vajan figured nobody would search Biggs for anything important]. During her most recent stay with the bandits, she'd heard that Tiger had some "unfinished business" he wanted to take care of and would be attacking the Mask's fortress while the Mask was attacking the keep. Thorongil and Beeel hogtied Vajan, and they all headed back toward the keep to try to ambush the bad guys when the attack got underway.)
The walking wasp finally reached the shrine area but was killed by the thieves. A small explosion near the west gate burned off the stinking cloud and killed the five remaining guards. Bandit archers moved into the gate and opened up on Frankel and Lorcan. An unseen attacker hit Harthika with a poisoned blowdart, but she saved, and Ahlonna went into the garden to investigate. The stable went up in flames. Beeel checked on Tymark's and found eight halbardiers trying to force their way inside. He killed five and smiled at the other three, and the survivors ran away. Lorcan's random electricity wand created a ball of lightning that blocked the west gate again, killing another squad of eight halbardiers and blocking the advance of a half-dozen zombies. This also blocked Beeel's halbardiers in, so they threw down their weapons and surrendered. (One of them also asked Beeel if he were Shatru's brother.) The battering sounds outside the east gate stopped, presumably due to Thorongil engaging the forces there (something like wereboars).
Meldrim checked with Harthika and learned that the shrine wasn't shielded against teleports or dimdoors and thought the Mask might have done inside. He took the key from Harthika's belt and unlocked the main door, but Beeel came back in time to go in and do the actual checking. Harthika also moved inside the shrine, looking for bonuses on her parries.
With nobody left watching the halbardiers, they picked up their weapons and went back to breaking down Tymark's door. Lorcan invisibly arrived on the scene with a phantasmal force of Beeel, and they ran away again. The lightning ball dissipated, and the zombies advanced and engaged Lorcan. Ahlonna tracked down the blowgun wielder (a woman in brown), beat her up, and let her escape over the garden wall (using a rope ladder, which Ahlonna later destroyed) in exchange for a pair of cat's eye gems. A priest with a pet bear appeared at the west gate. Beeel completed his sweep of the Belhor shrine and found no hostiles, so he flew off to hold the again-undefended west gate. Meldrim locked the shrine again. Zenig heard some noises coming from Tymark's second story and went upstairs to investigate.
The halbardiers showed up near the Belhor shrine, and Meldrim dropped a sleep cloud on them and took away their weapons. Zenig found the Mask looting Tymark's bedroom and gave a shout about it but failed to save against a hypnotic effect coming from the mask. Meldrim heard Harthika crash to the ground inside the shrine, presumably nailed by the phant killer. Lorcan blew off Tymark's door with a gnomish flare and tried to tumble over Zenig's firewood barricade (in plate mail) but failed and landed on his face. Zenig dodged an attack from the Mask and tried to grab something that looked valuable in an attempt to draw her out of the bedroom; he thought he grabbed a nice-looking hammer, but when he got back into the hall his hands were empty.
Beeel engaged the priest, and the bear engaged Beeel. The priest tried using a command spell on Beeel and was shocked when it didn't work. (He was also surprised to hear shouting about the Mask being at Tymark's, since he'd thought the Belhor shrine was the target of the attack.) The bear got Beeel into a hug, and they started trading squeezes and max damages.
Thorongil flew over the east wall, dumped off a bunch of axes, and headed for Tymark's. Frankel tried to squeeze into Tymark's but was blocked by a trio of zombies. Zenig again tried to grab something of Tymark's and again came up empty. The priest hit Beeel with a rod with the head of a poisonous snake; when Beeel saved, the priest tried to surrender, but Beeel killed him. Ahlonna started moving from the garden toward the keep and encountered a pair of goblins, who were no match for her.
Meldrim continued guarding the shrine and watching the gates, Frankel finished off the zombies and then headed for the burning stable to check on the horses there, and the rest of the party converged on Tymark's bedroom. (Thorongil was flying outside the window, which was open but blocked by a set of bars.) Ahlonna esensed some sort of presence, Lorcan got a vague reading on detect magic, and Thorongil noticed a very small set of tracks in the dust by the window; apparently the Mask had gone invisible and used a potion of diminution to begin her escape. Lorcan tried scanning with the monocle; he got a nasty headache and went deaf, but the crosshairs went active on something.
The halbardiers woke to find Meldrim looming over them.
Derdriu reappeared, whatever bandits were still outside gave up and scurried away, and the fight looked to be pretty well over. The Belhor shrine showed no signs of tampering or defilation. Derdriu used a scroll of raise dead on Harthika, but the five percent failure chance kicked in and Harthika stayed dead.