Location and loot

Take the crossing point at the Route du Renouveau and go south into the house. If you do not yet have this crossing point, it is located northeast of the bridge. You will have the hatch just to your right when you enter the house. Be careful, it is not super visible.

Then take the hatch, search the area and head to the left. You will notice two stone seats, install one of your characters in each (remember to separate your group). The wall will then open, you can take a poison potion if needed but the damage is not huge. You can then collect the loot, including a rare ax and a lot of precious stones!