Summarised from user Diefenbaker101's guide on TrueAchievements
Must be completed on hard mode.
This achievement can be completed in part 4, but it's suggested to wait until part 6.
- In the Occult Book Store you'll find a head near the counter. This is Sepp the Navigator (pick up the eye drops on the counter while you're here as this will get you on your way to the 'Mean Person' achievement)
- Travel to the QuickiePal and pick up the bear repellent on the counter.
- At the very beginning of Part 6, use your map to travel to the mansion. Outside, you'll find a rusty shovel to pick up.
- Travel to the Trailhead, use the bear repellent and make your way into the Spooky Forest. Make sure you can see Sepp's head in your inventory as it'll guide you where you need to go.
- Some paths are close together, so look carefully and the head will angle towards the correct one.
- After a few screens you should come across a unique area with a plaque on the right and a notice board to the left, on the ground in between you'll see an 'X' that marks the spot. Looking at the plaque will unlock the achievement.