Doomsday in the Depths

An intrepid scientist has disappeared, and the PCs need to find them. Following their trail leads to a certain spot along the edge of the Arc, the kilometers-deep trench carved into the surface of Meptus decades ago in a great war—and then into the Arc, where the PCs find a secret outpost hidden deep near the bottom of the trench far from prying eyes on the surface. A splinter group of the Grand Hinesta, one of the factions involved in the war that created the Arc, established this outpost to develop a terrible weapon that they plan to use to belatedly claim victory in the long-ended conflict. The scientist came here investigating a signal they detected originating from the outpost, but finding and rescuing the scientist may now be a much lower priority than stopping the outposts' residents from deploying their doomsday device that could reawaken old hostilities and further devastate the already damaged world.