The Posse start the campaign on a train, which is derailed by a cave-in. After recovering from the wreck, they discover a tunnel that leads them to a virtual army led by Darius Hellstromme, on his way toward the City of Lost Angels to win the Great Rail Wars. They are welcomed into Hellstromme’s camp and follow as he finishes tunneling under the Rockies to complete a transcontinental railroad. Hellstromme’s rail-builders are not exactly welcome in Lost Angels, though, and the heroes then bear witness to the Battle of Lost Angels, where the first Ghostfire bombs are detonated.
Eventually a truce between Grimme’s forces and Hellstromme’s is established and Hellstromme secures an exclusive contract to ship ghost rock from the Great Maze. Meanwhile, the Posse begin to discover the dark nature of Grimme and his cult. Eventually, they are inducted into the Explorer’s Society by Captain Roderick Pennington-Smythe, and discover a series of glyphs scattered around the Maze.
The glyphs are linked to powerful earth spirits: properly marked, they can trigger an earthquake powerful enough to shake all of California and bring a flood of water from the Maze into Lost Angels. If this is done when all of Grimme’s thirteen elders are in the cathedral at the center of the city, it will kill both them and Grimme.