After completing some additional activities in New Hope, the group reassembled (without Garrick, who remained in New Hope) and headed for the southern end of the Tuskwater to investigate a strange disturbance reported by the lizardfolk there. They were provided with a boat and a lizardfolk guide, who told them that animals and fish seemed to be avoiding the area, and there were unsubstantiated tales of people being used involuntarily in strange ceremonies.
As the team explored the lakeshore, they found evidence of cut trees that someone had attempted to disguise as the work of beavers. They also discovered barbed stakes buried in the lake bottom near the shore, clearly intended to harm anyone who waded into the water. They rowed out to the location where an underwater disturbance had been reported. Silverleaf cast water breathing on everyone but Landon, who chose instead to swallow a potion that transformed him into a boggard. Silverleaf donned his gloves of swimming and climbing, while Tahjah and San’Kari put on rings of freedom of movement. Leaving their guide and Cyst on the boat, they swam down to the lake bottom.
At the bottom they quickly spotted a whirlpool of swirling silt. Closer investigation revealed that a creature was responsible for this, but to their surprise this creature proved to be a bulette. Tahjah was able to converse with it, aided by Landon, who had cast comprehend languages on himself. The bulette revealed that it was being compelled by another creature to dig a tunnel to the Tuskwater all the way from the Hooktongue Slough area. This other creature also gave the bulette the ability to breathe underwater. Since the bulette was being forced to dig, the group decided not to harm it and instead to set it free. Tahjah used dispel magic to release it from the dominate monster effect that was compelling it, and then encouraged it to swim to the surface. Tahjah swam along with it to help direct it toward the shoreline.
Landon remained near the opening to the tunnel, watching it closely. Suddenly a large creature emerged swiftly from the tunnel and struck Landon with a tentacle. He was also engulfed in a cloud of mucus exuded by the creature, which caused his flesh to turn transparent and slimy. The rest of the group turned their attention on this creature, which they identified as an aboleth. Silverleaf summoned a giant octopus, which grappled the aboleth in its tentacles and bit with its beak, though it was unable to affect the aboleth with its poison. He also summoned a giant moray eel to bite it. San’Kari was able to fight as he would have on land thanks to his magic ring, and he struck the aboleth repeatedly with his axe, doing it grievous harm. Landon also attacked it with his dagger and left it bleeding, and Thim swam in to strike with his sword. A swarm of electric eels and four sahuagin swam out of the tunnel to aid the aboleth, but San’Kari slew several of the eels and Tahjah then commanded the aboleth and the sahuagin to stop attacking. While the aboleth was unable to fight back, San’Kari sliced it to pieces.
Three of the sahuagin were slain, but the last was questioned and set free now that it had been released from the aboleth’s control. It revealed that the tunnel had been under construction for months. It also indicated that there might be other aboleths at the other end of the tunnel. The group discussed how they could close the tunnel opening, concluding that San’Kari’s magic item of stone shape could be used to block it, while Landon used his native dwarven engineering skill to ensure that the blockage was sturdy.