Mission Name: Adventure in the Forest Follow-up (Find the Bad Guy of Vimo Village)
Step 1:
You have to finish the Forest Book series before you can take on the task.
When you're done, open the forest book in your backpack; As shown in the picture:
If you don't [tick] it, you haven't done it yet.
The bad guys are located in the following picture:
Step 2:
After finding Alfonso to talk, let him go and you can get the achievement.
Step 3:
After that, teleport to Hennalana, where there are two bloody dogs.
There is a glowing point, investigate it, and you can get another 20 rough stones.