Allustan is keenly interested in exploring the Whispering Cairn following the Diamond Band’s explorations there, but first, he needs to consult with an old friend in Blackwall Keep. He asks the heroes to go south to find his former comrade, Marzena, and bring her back to Diamond Lake; the road along the Mistmarsh’s edge is unsafe, even for a powerful wizard.
The heroes arrive at Blackwall Keep to find over two dozen lizardfolk assaulting it. The Diamond Band comes to rescue the survivors in the keep and repels the lizardfolk in successive attacks. Once the keep is secure, the surviving guards tell them several soldiers (including Allustan’s friend) were carried off and need to be rescued. While the heroes rest up following their battles the previous day, an assassin slips into Zerric Splintershield’s room in the night and slits the dwarf’s throat. Luckily, his cousin Bors hears the commotion, and is able to respond in time to leave Zerric alive, if now in possession of a nasty scar. The following morning, the Commander of the keep urges them to free the captives, while he uses an emergency scroll of teleport to report the news to the commander of the Diamond Lake garrison and ask for reinforcements to be sent south.
The heroes also discover that the last Commander of the Keep was a former cleric of Terak named Theldrick, the very same cleric who now serves Naran, and who operated out of the dungeon in the Dourstone Mine beneath Diamond Lake. The heroes also learn that Theldrick turned away from Terak after his wife was kidnapped from outside of Blackwall Keep by orcs some 20 years ago—around the same time that Ivagmar was born.
The trek to the lizardfolk lair takes more than a day, but the numerous lizardfolk leave a relatively easy trail even through the swamp. The lair is large and partly submerged, and the lizardfolk defend it vigorously. The Diamond Band learns of a schism within the lizardfolk tribe, and of the alliance between the lizard king and the black dragon Ilthane. The Diamond Band defeats the corrupt king and rescues the tribe’s eggs from a terrible fate, securing the cooperation of the Mistmarsh tribes and rescue the prisoners.
Returning to the keep with the freed soldiers, the heroes find the survivors at the keep are terrified of a creature in the basement that has been snatching them one by one. The heroes descend into the basement to discover a vile undead creature known as the spawn of Kyuss and slay it, but not before learning first-hand how dangerous they can be.
When the Diamond Band brings Marzena to Allustan, he is grateful for their help and eager to hear the news of their most recent adventures. Marzena tells Allustan what’s she’s heard about green worms in the Cairn Hills, but unfortunately her news offers little new information apart from confirmation that spawn of Kyuss are increasing in number throughout the Cairn Hills. This information and the heroes’ report convinces Allustan that there is something larger going on, and he tells the heroes about an “old friend” in the Free City, a sage named Eligos who knows a great deal about strange monsters. Their next step is to visit Eligos in the Free City and share Allustan’s compiled notes and their own experiences. Armed with this information, the sage ought to be able to determine what sort of threat the green worms represent to the region and how it can be countered.