the misson is to go find aeerie( or something like that)'s crystal key, fisrt you have to find it then go put it in a key hole, its gonna work like going to go to breakwater beach with the key.

the crystal key is at the ( the)chasm.

then put the key in the hole:

then you get to go to the new place:

i think the pics might not work... so let me just explain it.
1) fall in the chasm
2) get the key
3) go to the in order to go to mage barrow, there should be a key hole in it. get your key and put it in.
4)you will arrive at a new place.