The Avowed Fort Northreach storage key isn’t far away from the door that it unlocks, though it's possible to overlook it if you aren't being thorough. Opening the storage room isn't critical to your quest but it's worth doing to get a bit of armor that, even if you don’t wear it for long, will help in the opening hour of Avowed – or you can scrap it for upgrade materials later, which will help a little towards upgrading items in Avowed. Below, I've briefly explained exactly where to find the Fort Northreach storage key and how to use it.

From the Fort Northreach storage room door in Avowed, head through the busted brick wall into a large room with a massive turquoise crystal inside. To the right of the crystal, you'll spot an open square-shaped doorway that leads to the fort exterior, but you need to look at the dead guard slumped nearby. Loot this guard's body and you can grab the Fort Northreach storage key, as well 20 copper skeyts and a common round shield.

Now you can run back the way you came to the first room you dropped into, where you'll find the storage room door and can unlock it now that you have the key in your inventory. Open the door and you'll immediately spot the a chest ahead, which you can open to get a common breastplate – not the greatest reward, but some sturdy armor will help you for what's ahead, so make sure you put it on and equip the shield you should have swiped from the dead guard.