Location: Eden’s Pyre
Once you have arrive in the location, you’ll notice corpses scattered around the area. Ignore them for now then examine the clue from the yellow container to start this mission. You’ll then have to find all 5 New Edener corpses and throw them to the pit. While doing this, you’ll get attacked by some feral animals around the area. Take them out to resume your work.
Four of the corpses are found in the immediate area. The last corpse is found on top of the wooden scaffolding. You can reach it by climbing the hill behind the pyre.
Throw the last corpse to the pit then set it on fire by throwing a molotov at it or using a flamethrower. Wait for a few seconds and the entrance to the cavern leading to the stash will be opened. Loot it to complete the treasure hunt.