Hi guys:
Unfortunately, I don't know a lot of the details. It's an AU that takes place in the past in the west. I believe Steven Ellison is lost and injured - broken leg? - in the desert, in the territory of a Native American group who are watching him die due to earlier hostilities. William has contacted Jim to help look for him. A good part of the story takes place in the private car of a train that William has rented. At one point, the train reaches a station at which part of William's business operates, and it's discovered that there is corruption going on without William's knowledge. Blair is an important part of the story, but I can't remember what he does, or whether the story is slash or gen.
Thanks guys!
found, Oak Creek Canyon, second in the Bitterwood Creek series by Arianna.
http://archiveofourown.org/works/310801/