From the publisher's website:
A Short Adventure for Four 18th-Level Player Characters
Earthquakes, tidal waves, and volcanic eruptions have suddenly wracked Porthaven, a city normally known for its mild weather and calm seas. The root of the problem is an arcane machine built to protect the city 300 years ago by extraplanar creatures called modrons. Now the machine has run out of fuel, and it's up to the PCs to obtain more by visiting each of the four elemental planes. Can they get the machine working again before the city of Porthaven is wiped from the earth? Drop the latest miniadventure for D&D v3.5 by Mark A. Jindra into any coastal area with mountains nearby. Suitable for four 18th-level characters.
Three hundred years ago, the coastal town of Porthaven was built on a site that was advantageous for trade but both geologically and meteorologically unstable. A volcano in the nearby mountains threatened to erupt and destroy the town, and earthquakes, tidal waves, and hurricanes were common. But the doughty townsfolk stayed and rebuilt after each disaster, determined to make the town prosper.
Eventually, a powerful sorcerer named Khyber Mercane saw the carnage that the unending natural disasters wrought and decided to do something constructive. Recalling that he had once met some extraplanar creatures called modrons that favored order over chaos, he contacted them to see whether they could help. After discussing various options, Mercane struck a deal with the creatures: They would build and maintain a machine that would keep the town safe from the chaos of natural disasters, and in return, the townsfolk would keep a library of knowledge to pass along to them every year.
The machine worked, and the volcanic activity ceased. The harsh windstorms that had previously blown through the valley softened to mild breezes, and the high waves that had battered the shoreline shrank to harmless ripples before reaching the coast. The earthquakes that were once common occurrences no longer shook the land. Even the seasons seemed to even out so that the temperatures rarely reached uncomfortable extremes. The crews of ships that had been through rough seas and stormy weather found the calm waters and friendly people of the town a welcome sight, as did many weary travelers along the coast. The town grew rapidly and soon became a bustling city.
For the first seven years, the modrons sent a representative to gather the accumulated knowledge and service the machine annually. Then the visits abruptly stopped. Khyber left to see what had happened to the modrons, but he never returned.
Worried about the safety of the untended machine, the clerics of Wee Jas built a temple around it to shield it from unauthorized visitors. But though this tactic did safeguard the machine, it also removed it from the people's sight, and eventually it was forgotten by most of the populace. Only a handful of the church's priests still know of its existence, and fewer still know its true purpose. Sister Mara, the most senior member of the clergy, has been studying the history of the machine, and she has recently rediscovered its purpose and a few details of its maintenance. Realizing that the machine had not been refueled for many years, she warned the townsfolk that disasters might be imminent, but they scoffed at her dire predictions.
A few weeks ago, the machine ran out of fuel and shut down entirely. Shortly thereafter, Porthaven experienced its first earthquake since the activation of the machine, but the tremor was small and went unnoticed by most of the city's residents. The next sign that the city had lost its protection was much more obvious. This morning, the nearby volcano suddenly erupted, spewing forth a hellish river of molten rock and fire. The sky grew as black as night, and fiery ash began to rain down from the heavens. The earth beneath the city heaved upward, toppling structures and feeding the fires caused by the flaming debris. A great wall of water from the sea laid waste to Porthaven's docks, leaving many seagoing vessels and coastal homes either at the bottom of the bay or in ruins in the city's streets.
Currently, the city officials are busy evacuating the residents through several magic portals that are normally used only by merchants and adventurers. But these few portals cannot accommodate everyone, and the rivers of lava will reach what is left of the town in only a few short hours.
Not to be confused with Force of Nature