Balthule's letter is dire. This Cult of the Dark Strand is a thorn in my side that must be removed. I have been dealing with some of the Dark Strand scum northeast of here at Ordil'Aran. One of their number possesses a soul gem that I believe holds the secret to the cult's power.
Bring it to me, and I will be able to decipher the secrets held within.
Hmm, some dark magic enchants this soulstone. Let's see what's trapped inside, shall we?