Speak to Mildred the Cruel inside the Forlorn Mine.
Our deal is made then, <name>. You help me get out of these chains and I'll help you find your little green friend.
The Hyldnir who runs this mine is known as Mildred the Cruel -- and with good reason.
Tell her you've been sent to lend a hand with the mines. Do whatever she asks until she trusts you with the keys to my shackles.