Served Cold

Background
"Captain Veleth told me that Adril Arano, Second Councilor of Raven Rock, wanted to speak to me immediatly. I should find him and discover the reason for his urgent message"

Quick Walkthrough

 * Speak to Adril Arano
 * Speak to Geldis Sadri
 * Wait inside Ulen Ancestral Tomb
 * Discover the identity of the tomb's visitor
 * Report back to Adril Arano
 * Recover evidence from Severin Manor
 * Bring the evidence to Adril Arano
 * Meet up with the Redoran Guard
 * End the threat to Councilor Morvayn
 * Return to Adril Arano
 * Follow Adril Arano
 * Speak to Councilor Morvayn

Detailed Walkthrough
After completing the quests At the Summit of Apocrypha, March of the Dead and The Final Descent, Captain Veleth will request that the player speaks to Adril Arano, the Second Councillor of Raven Rock immediately. Arano can be found either walking around Raven Rock or in Morvayn Manor, and is worried that members of the Ulen family are present in Raven Rock, seeking revenge for the execution of their ancestor by a member of the Morvayn Family, and suggests that the player speak to Geldis Sadri, at the Retching Netch Corner Club.

Upon talking, Seldri will suggest a plan to identify the member(s) of the Ulen family who may be present on Raven Rock, suggesting that the player hide within the Ulen Ancestral tomb, as someone had recently been leaving offerings within it. Upon waiting within the tomb (for any amount of time), the Dragonborn can witness Tilisu Severin enter the tomb, and who upon interrogation, will insist that she is not a member of the Ulen family, that she is just leaving offerings for the dead.

The Dragonborn must then report back to Arano, who will request that the Dragonborn search for evidence within the Severin's home, Severin Manor (''NOTE: The game can freeze upon approaching Severin Manor at this point during the quest, so saving before approaching the house is advised). ''Severin Manor is the house closest to the Earth Stone, and upon entry, the player will be attacked by Tilisu and Mirri Severin, who must both be killed (the player should make sure that they loot Mirri's remains, as she is wearing a rare set of Dunmer clothes & shoes). The evidence needed can be found within the Severin Family Safe (a key can be looted off Mirri Severin's remains) which is located within the master bedroom, in the form of a letter titled "The Ulen Matter".

Upon returning to Arano, he will send the player to meet up with two Redoran Guards at Ashfallow Citadel, located north of the Sun Stone. Upon arriving at the fort, the Redoran Guards will be dead, killed by Morag Tong Assassins, who occupy the fort, of which there are two outside, who will attack the player (this is the only chance to get Morag Tong Armor, which can be looted off the remains of the assassins and found within a couple of areas within the fort). The fort itself consists of a set of stairs leading two a corridor blocked off which several sets of gates which are protected by Morag Tong assassins. These gates must be lifted with chains, which can be found in the following places: At the end of the corridor is the final room, where Vendil Severin can be found, along with two Morang Tong assassins. Upon killing the, the quest will update, telling the player to return to Arano. The player should loot the remains of Vendil, as he has the following unique armor: Upon returning to Arano, he request that the player follow him to speak to Councilor Morvayn, who will reward the player with Severin Manor and a levelled amount of gold.
 * On the wall in the first room of the left-hand side of the corridor
 * The second room on the right-hand side of the corridor, which is trapped.
 * Next to entrance to the second door on the left-hand side of the corridor, close to the gate(s).
 * The final two are behind pillars located next to three swinging door traps, on the right hand side of the passageway.
 * Chitin Armor of the Eminent Knight (Increases Heavy Armor Skill by 20 points)
 * Chitin Bracers of Eminent Wielding (One handed attacks do 30% more damage)

Trivia
It is apparent through doing this quest that the Dragonborn has a reputation in Raven Rock due to there previous exploits in the town. This can be identified most clearly through talking to Councilor Morvayn and the initial request from Adril Arano.
 * This quest is the only way to obtain Morag Tong armor, along with unique variants of Chitin Armor which can be looted off Vendil Severin. The player can also find a rare set of Dunmer clothes (including shoes) by looting the remains of Mirri Severin.
 * Severin Manor is arguably one of the best houses available to the player for ownership in Skyrim, as it includes a smithing area, more weapons racks / mannequins than any purchasable house, and a lot of storage.