Quest Giver: San Matheus, reading a letter outside the house.
Go and have a conversation with the Natives who live in a forest near San Matheus. You will need to find the inquisitor Claudius’ house. Head to the marked area on the map and pick up the letter. When you come outside home you will come across a bunch of inquisitors but it won’t end up in a fight.
Head over to inquisitor Claudius’ office and open the chest to find his notes. Go back to the natives and tell them what happened. Inquisitor will show up so you need to deal with him. Win the fight and speak with the natives to complete the Inquisition Side Quest. You will get +2 reputation with the Natives and 1600XP.