Heading from the Dweller Camp towards Brightwall, you will eventually reach the border of the snow. Pay attention to the left side of the path - you will find a stone wall there and a hole in it. Go through it. The path behind it will lead you to a cave full of wolves . The key is at its end .
After going out of the cave mentioned before, jump off the cliff on the left . The next key is behind the pile of logs .
Head towards the monorail station  and turn right before it. That way you will find a mountain path leading to the silver key .
The next one is hidden in the Mercenary Camp . It's below the observation tower , nearby the arena where you fought with Saker.
In The Hole (the location beneath the monorail station), move forward all the time until you reach a square with barrel stands . Go round it and you will find the next key .
Beside there will be another gate, requiring the engineer key . To find it, go forward until you reach the arena where you fought the Hobbe mages .
Cross the bridge  and turn left. The item will be at the end of the path. Use it to open the mentioned door and pick up the key behind it .
To gain the last, head to the monorail station in Millfields  and climb up the stairs. The item you seek is behind the corner of the building with posters .