From publisher blurb:
Swamp Dungeon of the Bandit Lord is a short Swords & Wizardry WhiteBox adventure designed for 3-6 characters of 1st through 3rd level (about 12 levels total). The adventure involves exploration of a dungeon that has been magically transformed into a swampy cave complex. The characters can expect to encounter a wide range of monsters and challenges, so a variety of classes is recommended.
Note: This adventure takes place in Willow Valley, a fantasy sandbox that is fully detailed in the WhiteBox Omnibus published by Barrel Rider Games. Willow Valley is centered around Willow Lake and is home to humans, elves, dwarves, halflings, and other fantasy races. The valley setting can be easily adapted to any fantasy campaign world.
In dark times past, after the great dragon Agathareon fell to the arch-mage Asagrim the Abjurer, the beleaguered folk of Willow Valley were plagued by bandits and raiders. One of the most wicked was the bandit lord Kaven Redblood whose stronghold of Redblood Keep stood atop Tallrock Hill, allowing him to prey on travelers along the Citadel Road.
Kaven's ambition was to crown himself King of Willow Valley, but he knew that the people would eventually rally against him. Therefore, he ventured deep into the Swamps of Sithiss to seek an alliance with the lizardmen tribes who dwelt there. The Sithissian shaman gave Kaven the seed of a sacred cypress tree known as the Heart of Sithiss. The shaman told Kaven that once the seed was planted and nurtured, the lizardmen would honor him as a brother and the very Swamps of Sithiss would come to his aid in times of need.
Kaven's return to Redblood Keep did not go unnoticed by the free folk of Willow Valley. An alliance of Willowford militia, Burrowmoor halflings, and Citadel dwarves laid siege to his stronghold and reduced it to rubble, forcing him to take refuge in the dungeons below.
In desperation, Kaven planted the magical cypress seed in a deep dank cave, hoping its magic would conjure up a Sithissian army to fall upon his enemies. Unfortunately for him, the Sithissians had no intention of honoring their bargain. The seed was cursed with a magic that was designed to transform the very earth into swampland. The moment it was planted, it sucked the life from Kaven and his followers and used this energy to magically transform the caves of Tallrock Dungeon.
Unable to gain access to the dungeons, and having seen no sign of Kaven or his followers for weeks, the Willow Valley alliance grudgingly returned to their homes. Time passed, new threats arose and were vanquished, and the siege of Redblood Keep eventually became a distant memory known only to a few.
Cut off from the world outside, the denizens of Tallrock Dungeon slipped into a magical slumber. But all the while, the magical cypress continued to grow beneath the earth, its magic building as it waited to be unleashed.
Recently, a group of dwarven miners from Stoneaxe Citadel came upon a hidden staircase and a secret entrance into the dungeons of Tallrock Hill. As soon as they opened the door, the tree's magic burst forth upon the land, draining the life force of the dwarven miners and using their energy to revive the swamp creatures who dwelt within its dungeon home. Now, this magic has begun to spread. . .