Quest Stages - TGTQ04 (Summerset Shadows)

10 Speak to Torsten Cruel-Sea
Torsten Cruel-Sea, a wealthy merchant residing in Windhelm, has requested assistance from the Thieves Guild.
20 Speak to Niranye
Torsten Cruel-Sea's daughter Fjotli was slain and robbed of a silver locket by a Thieves Guild hailing from Summerset Isle. Calling themselves "The Summerset Shadows," they are looking into expanding their influence in Skyrim.
30 (Optional) Discover leverage to sway Niranye
40 Travel to Uttering Hills Cave
Torsten's daughter wasn't slain by the Summerset Shadows, but their leader, Linwe, has them robbing the dead of their valuables. Linwe and the rest of his guild have established a hideout in Uttering Hills Cave.
50 Recover Fjolti's Silver Locket
60 (Optional) Destroy the Summerset Shadow's Banner
I've slain Linwe and obtained Fjotli's Silver Locket. This ends the presence of the Summerset Shadows in Skyrim.
70 Return to Torsten Cruel-Sea
200 The locket has been returned to Torsten Cruel-Sea, and the Thieves Guild can now count on him as an influential ally in Windhelm.