A couple of adventures ago, the party was involved in a theft from The Library of Zorlac, a handy-dandy structure/adventure from Zak's Vornheim book. Their client, aside from being a bit strange, paid in good coin and the group didn't seem too disturbed by the potential danger of filching a book from such an obviously powerful figure -- the job actually went pretty smoothly, as the client knew exactly where the book was and a careful stakeout job enabled them to strike at a point when the library (Magic, in case you were wondering) was unattended. The resulting flight through The Warrens was seen as good maneuvering to lose any pursuit, with the added benefit of allowing the mage to hide Sibley's Field Guide to Minor Demons (that he had grabbed behind the client's back, against his instructions, during the robbery) in an inconspicuous spot of loose stone and mortar.
They were a little perturbed when the client opened a door and was then observed to leap through a strange hanging portal, disappearing as he fell through (apologies as I've forgotten who originally came up with this particular portal concept, my brain isn't what it used to be), mainly because they'd only been paid half up front.
Pursuit was put off as there was no way for them to determine where the portal might lead to and hell, there are plenty of other opportunities to pick up coin in Fenrecz. Of course, once the party is done being caught in the centuries-old death-dream of a dinner party cum demonic sacrifice gone horribly wrong/right (depending on what you're looking for from a dinner party or not -- if it's tasty tasty souls, the result was definitely "right"), they'll have the small matter of being tracked to one of their hidey-holes (probably the Tainted Bone, where they're on good terms with the Order of the Distributed Brothers of the Masses) by a desperate Corsica Nyne, who has the abilities to pick off the party one by one unless they agree to help her recover the volume stolen by the man (?) calling himself Vistula Cronin.
Should the party tell her where the book has been taken, she will attempt to force the party to accompany her through the portal. If they do so, they will have a short fall from a hanging portal into a half-destroyed chamber in a ruined city carved out of volcanic stone. The pitted stone structures lie on a barrier reef island, surrounded by the open ocean of the tropics. Rudimentary searching of a mostly-intact structure near the portal will uncover evidence of a camp -- ashes from a fire, small pieces of garbage and detritus, some odd scrape marks indicating that something, perhaps barrels, were moved to block the entranceway and in a couple spots, blood stains.
With the island sloping down slightly from the center, the ruins have scattered paths and stairs going up a couple hundred feet before petering out into the jungle. At the highest point of the city is a large T-shaped foundation, any roof or walls long since destroyed. At the junction of the foundation is a large flat circular stone, notable in that it is a lighter color than the other rock, which is vaguely maroon, and also in that it's smooth instead of pitted. Diligent searching around this rock will uncover a portion of the foundation that can be pried up by 2-3 strong men and a strong lever. Under the flagstone will be found: five large cones of incense, three great clay pots filled with aromatic oil and two kris blades, ornately carved and decorated with red and blue coral. Scattered colored fibers indicate that these items were once wrapped in some sort of tapestry or blanket.
The city overlooks a small sandy beach, with the rest of the island being covered with dense jungle with occasional rocky outcroppings. The island is no more than six miles across and is vaguely circular. Searching the beach below the city will show evidence of a small (15-20') boat having been pulled ashore.
Between the island and its barrier reef is a shallow shelf, ranging from 5-20' deep. Continued observation will reveal the movement of several large (4-6') and brightly colored nudibranchs. These slugmen, of which there are around three dozen, live on the inner side of the reef and subsist on eating fish and large sponges, which they grow on the sides of the reef. These sponges provide them with a powerful toxin that they can excrete through their skin -- any skin-to-skin contact will result in exposure to the poison, which has a paralytic effect that will be fatal in a very short time (2-5 rounds) to any air-breathing creatures (due to drowning). They won't attack anybody who enters the water, although 2-6 slugmen will track their movement from a short distance.
The slugmen, who communicate through pheremones released into the water, will be open to telling anybody who manages to "talk" to them (a wild Rego Auquam should work in my Ars Magica-based system, I leave it up to the individual DMs as to how effective Comprehend Languages and its ilk should be) that some surface-walkers showed up some time ago in a large vessel outside the reef, used a smaller vessel to travel to the island, then left again 5 days later. They should be able to give a decent idea as to which direction the large both arrived and left. They know nothing about the ruin on the island or anything else about what's on land.
If anybody chooses to spend the night in the ruins (or worse, the jungle), the Buta-Kala come.
The first sign that something is going on will be floating orbs of light visible deep in the jungle, floating between the trees. If the party wanders after the lights, they will attempt to lead them further and further from the city before the Buta-Kala ambush them. If left un-investigated, the lights will eventually form into hanging lines, as if a festival were taking place, faint sounds of revelry, tinged with animal-like cries, will drift into the city. If the party goes into the jungle now, something equivalent to Bilbo disturbing the elf-king's feast will take place, culminating in an ambush. Otherwise the noise will slowly increase until it sounds nearly on top of the ruins, at which point it abruptly stops. A minute later, the Buta-Kala come out of the jungle and attack anybody they can find.
Next time: Wait, what do those things we found do? And who are the Buta-Kala?