Mission picked up in Sawtooth Cauldron (I think) to find 4 pieces of a treasure map, then follow the clues.
Under the acid soaked railway: 0:05
In the warehouse on the shore: 0:30
In the digger’s shadow: 1:10
Within Dahl’s bloody sixth: 1:40
Also, if you’re listening to the commentary, I found the rest of the map. Different mission. Minecart Mischief