As they descended into the tunnel (see ST14. Brains at the Brewery), Amos Black decided to stay behind due to a twisted ankle incurred in the climb up the rocks. Undaunted, Sacha Cresswell, Kuven and El Graeve all continued to head down into the darkness. The tunnel was large enough for Sacha Cresswell to stay mounted on his spectral steed, and they trudged on downwards into the depths. They quickly lost all track of time, something that they found quite disconcerting; they could not tell if they had been walking for one hour or eight. Their journey was interrupted by a bulette, which tunnelled out of one of the side walls behind the party, and attacked them. It proved to be quite dextrous, as it jumped away and then back, trying to slam Kuven and the quickly-dismounted Sacha Cresswell underneath its immense weight, however El Graeve was able to find a weak spot, and shot an arrow into its eye, felling the beast, which promptly fell onto the still-prone Kuven. At this point, the party decided to stop for a night's rest.
They carried on, still unsure of how long the tunnel journey was taking them, until they found themselves in the largest cavern that they had ever seen. They found themselves on a high ridge, with the cavern's floor perhaps half a mile below them, dotted in strange glowing mushrooms the size of trees. Above their heads, swarms of birds could be heard flapping between the cavern's stalactites. This was clearly Khyber; a vast subterranean world, that connected to Eberron above in various places, though not in any way that made sense geographically. The ridge that they were on seemed to wind its way down as a path to the base of the cavern, where it met a pool of water several hundred feet across. On the other side of the pool could be seen a large bronze pyramid, heavily damaged by rockfalls that had collided with its outer surface. Thinking that this was a likely place for any survivors of the brewery to be, the trio followed the path as it wound down. As they came around one turn, they could see a pair of feet jutting out from behind a rock just ahead of them.
Kuven snuck ahead, and could see a wounded soldier wearing the uniform of Breland sleeping against the other side of the rock; and with a shock, he recognised her as Myra ir'Clain, who the party had previously met in the stockade in Darkreef Prison the previous year. She woke up at the sound of Sacha Cresswell and El Graeve approaching. She was immediately suspicious, as the last she had seen of them, she had sent them to the northern cavern on the prison island, and they had never returned. But Sacha Cresswell was able to convince her that he had been abducted by pirates, forced to drink a potion so he could leave the island safely, and was now working as a mercenary to earn his passage back home to Sharn. She didn't press further, but explained that she had ventured into the ruins where the myconids lived, in search of more of them so that they could be harvested for ingredients for the potion that let people leave the island. The previous day, her team had been attacked by Mind Flayers, and the rest of them had been dragged off to the bronze pyramid below.
Myra ir'Clain agreed to join forces to infiltrate the pyramid, so the trio became a quartet, and headed down to the pool of water. They started to swim across, but quickly realised that there was something in the pool, as a large tentacled creature swam towards them and attacked. Realising that they just needed to get out, the party swam as quickly as they could to the other side. Sacha Cresswell held back to cover the others, but found that it was surrounded by a strange mucus; he shrugged off the effects, but after that kept his distance. They all safely reached the other side, and entered the pyramid. Inside, they found a crossroads; taking the left path, they found themselves in a small room with a Mind Flayer, which immediately attacked them with a psionic blast. It wasn't able to stand to the onslaught of the party, however; after Sacha Cresswell tore through it, El Graeve finished it off. The room itself seemed vacant except for a strange pair of bells embedded into the wall. They headed back to the crossroads, and noticed that the other two paths each had a trip-wire across them; an arcane line could be seen in the brass wall that led back to one of the bells, which they realised was a way of alerting the guard.
Proceeding onwards, the party next came to a library, though all of the texts were written in a language that none of them could understand. In one corner of the library, they found a passage to a series of small chambers; in one of them, Kuven found an elf kneeling in prayer. The elf was strange; his bald face had been deliberately disfigured, and had the words "rebirth" and "beauty" tattooed across it in multiple languages. The elf was overjoyed to see them, and expressed gladness that more people wanted to become Mind Flayers, which he thought were the most beautiful creatures in existence. When he saw Sacha Cresswell he was particularly joyful, as he took Sacha Cresswell's tentacle hair as the first step in a transformation. The elf explained that he was awaiting his transformation, as the excavation work was still being undertaken. The party feigned knowledge of this, and also learned about a pool of water with the Mind Flayer tadpoles in it. They left the elf to his prayers, and carried on their exploration.
Next, they found a dining room and a kitchen, where several large insects were being turned into a stew. Beyond those, they found a make-shift dormitory; inside were some of the survivors of the brewery and some of Myra ir'Clain's soldiers. Amongst them was Radcliffe Conningsby, the owner of the brewery; he thanked the party for coming to their rescue, and told them what he knew. The Mind Flayer colony had been heavily damaged in a rockfall, and the Elder Brain was buried under the rubble. The few Mind Flayers that had survived had kidnapped some of his people to use as manual labour, to clear out the Elder Brain. The brewery had been betrayed by Perrin, who had lead the Mind Flayers to the island. The party realised that the elf that they had just met was Perrin, and mentioned this to the brewer. Radcliffe Conningsby agreed to take the survivors here outside, though he and two of the soldiers borrowed some weaponry, so that they could make sure that Perrin met the justice that he deserved. He also mentioned that Juria d’Vadalis had not been kept with the others, as the Mind Flayers were interested in her dragonmark.
The party's next discovery was a strange room with five pedestals in it, with a basin at the top of each pedestal containing a brain floating in a greeny-brown fluid. Kuven spoke to the brains, and they reacted, so they were clearly alive; but the party was unable to discern the purpose of this room. They carried on, and found the pool with the tadpoles in it. Realising that the hundreds of tadpoles here would be enough to devastate entire communities, El Graeve cast Spirit Guardians, and stood next to the pool. They watched as the tadpoles all died, one after another, and soon the surface of the water could not be seen for all of the bodies of the inch-long creatures. They carried on, and in the next room found the centre of the colony; a half-buried Elder Brain, with a dozen labourers digging it out with pick-axes, under the watch of a Mind Flayer. They attacked, but were quickly met with another psionic blast. El Graeve got close enough that the Spirit Guardians would also affect the Mind Flayer, but it responded by telekinetically throwing him thirty feet into the air and then dropping him. In the end, Sacha Cresswell was able to smite the Mind Flayer, and with its death the psionic control over the labourers fell. Free from its instructions, they instead attacked the Elder Brain, and it soon lay dead too.
The last room that the party found was some sort of experimentation room. It contained several teardrop-shaped pods, each containing a heavily-mutated body. All were dead except the inhabitant of the last one, which they realised was Juria d’Vadalis. Sacha Cresswell cut her out, and with everyone rescued, they made their escape. Myra ir'Clain and her soldiers headed back the way that they had come, and eventually the party was back at Conningsby Brewery. Amos Black met them there, and mentioned in passing that they had somehow been gone for a week. The workers got to digging out the storage building; although the ale in the building itself had not survived, it also had a cellar, and there were enough barrels there for The Demon's Mercy to take back to Second Chance.
The crew returned victorious, to find the pirate town on the verge of a riot. In their absence, the town had run completely dry, and Adira had struggled to keep order in the face of open revolt. The party were therefore hailed as heroes, and they found that they never had to purchase drinks in the inn again, as someone was always ready to offer them one, in gratitude for all that they had done.