From the WotC plot recap:
He was insane — absolutely insane. I can't imagine any other words to explain it. Why would any rational person unleash a plague on the innocent and unsuspecting? He was a rabid dog and had to be put down.
- - Teseryne Truesilver
- - Daughter of Talanthe Truesilver
- - Year of Rogue Dragons
The trouble began at the High Moon Market in Loudwater. I know, because I was there shopping for spiced oranges that had just arriver from Tethyr. The Order of the Jade Blade was there as well which was fortunate.
Out of the corner of my eye, I noticed three orcs arriving at the marketplace. A few years ago this would have started a panic, but not long ago High Lord Kalahar Twohands issued the Decree of Reception. The decree allowed orcs into town as a way to minimize the impact of the gray migrations of the orcs out of the High Forest. These orcs were shrouded in cloaks and smelled pungent and sticky. They started begging from the townsfolk saying that they needed help and a shaman.
One of the orcs started gagging, and the cloak fell from his shoulders. He was covered in large, seeping pustules. The gagging turned into vomiting almost pure blood. Everyone backed away as the pustules swelled and then erupted spraying puss and foul smelling fluids onto those nearby. I thought I was going to be sick right there when the orc literally exploded, flinging steaming, yellow ooze everywhere. The remains of the orc melted into the ground, leaving a mass of decaying ooze, hair and blood. It was the most disgusting thing I've ever seen.
The Jade Blade immediately stepped in and calmed the panic. While they did that, I ran to get Prior Athosar of the Houses of Morning. Athosar discovered that the orcs suffered from a variant of the slimy doom disease. The disease was extremely contagious and, even worse, was something for which we had no herbal cure. While Athosar could say prayers to cure disease, too many people were exposed to catch all of them. An epidemic was imminent.
The adventurers of the Jade Blade stepped forward and offered to track down where the orcs came from. They began following the back trail of the orcs. Many townsfolk remembered seeing them come in through the eastern gate. Beyond the gate, the tracks headed upriver. The group of orcs was once much larger, and the Jade Blade kept passing exploded corpses as they traveled further away from Loudwater.
On the outskirts of the Grey Highlands, the adventurers encountered more evidence of the disease. A half-dozen diseased orcs ran at them in a savage attack, whereupon they promptly exploded from the disease. By this point, I strongly suspect that all the members of the Jade Blade had the slimy doom.
While they were still scrapping the ooze off their clothing, one of the Jade Blade adventurers noticed that they were being watched by an orc crouching among the brush some distance away. They cautiously approached the orc to learn who she was and what was happening with the orcs. Their efforts were successful, as the orcish druid had no wish to fight. Her name was Kah'Liik, and she had managed to avoid the disease thus far. She had kept her distance from the other orcs and insisted that the Jade Blade stay away as well.
Through a conversation shouted back and forth, the freeswords learned from Kah'Liik that the disease was being spread by insect bites from a swarm of locusts. She was away from camp when the locusts came and so survived. The locusts all since died, but not before infecting the other orcs. The locusts came from a cave some distance to the north and she gave our heroes directions.
The cave turned out to be a twisted burrow of passages, probably created by umber hulks. They found the remains of thousands of dead locusts, whose shells coated the floor like a carpet that crunched under the adventurers’ feet. A hole in the ceiling led up to another set of caves, where the freeswords found Kranler Dhenta, held captive in a pit. Kranler was diseased and driven mad from torture. He raved that he was sent here to serve "the master," and that the master made him eat bugs. Our heroes pulled him from the pit and took him with them.
The master awaited the Jade Blade in the next room. The master was Drahmin Stonesplinter, a druid insanely obsessed with diseases and vermin. He built a laboratory of sorts to refine his contagions, including the slimy doom that he had unleashed upon Loudwater. Our heroes slew him and destroyed his experiments, including the crate of writhing beetle larvae that were infected with the disease. In his laboratory notes, Drahmin detailed the process of how he created the virus and was infecting vermin and eventually the orcs.
The Jade Blade returned with the notes and Kranler to Loudwater, where healers restored his sanity. He was a member of the Zhentarim who got caught stealing from his superior and had been sent to Drahmin as punishment. Drahmin used him as a test subject for the diseases that he was creating. Kranler had some interesting things to say about how the Zhentarim were funding Drahmin's research. Krenler is still with us in Loudwater and loyally serves High Lord Kalahar.
Athrosar and the town's healers pored over Drahmin's notes and found that they could make a cure but it required violet lotus, a rare herb that only grows in marshes along the Dragon Reach. The very next day, a Sweetwater Trader merchant caravan arrived from Orlbar carrying a large quantity of the violet lotus. They were willing to sell but only a premium. So Highlord Kalahar emptied the town's treasury buying the herb. The healers worked quickly and the epidemic was averted.
It was incredibly lucky that the herb just happened to be passing through town. Don't you think?