Back to Velen
You can pick up this quest in one of three ways, by reading the notice board at the Border Post or Oxenfurt, or speaking to the Captain near the Border Post.
However you start the quest speak to the Captain to find out that something is killing the Redanian caravans while they’re travelling along the main roads. As a reward he will give you a Letter of Safe Conduct which will give you access to travel over the bridges to Novigrad.
Searching for the Beast
Head out to the location on your map to find Alghouls around some wagons. kill them and then examine the area, including the chests and a body in front of a fancy cart. Use your Witcher senses to follow the footrpints towards the river where you’ll run into a group of Drowners. Take them out and continue searching for tracks on the other side of the river.
When you near the woods a Scoia’tael member will call out to you. The only way to answer without being attacked is to say that you want to see the commander. Surrender your weapons and they’ll let you through.
The commander Vernossiel tells you that they’re not killing civilians but Redanian soldiers who have tortured and killed the Scoia’tael. They are desperate for supplies which is why they’re raiding the caravans.
You can choose to fight the elves or side with them. If you choose to fight you won’t have your weapons equipped. There should be a sword lying around that you can grab.
If you side with the elves they’ll give you your weapons back and you’re free to move about the camp.
Return to the captain and give him an update. You can either tell him about the Scoia’tael or lie say that the monster in the area must have moved on. You’ll only get the Letter of Safe Conduct from him if you tell him about the Scoia’tael or kill them.