Laid to Rest

Background
Laid to Rest is a quest that takes place in the city of Morthal and can be obtained by speaking with the innkeeper, who will mention the burned down house nearby. Alternatively, Jarl Idgrod Ravencrone (or Jarl Sorli the Builder if the dragonborn sided with the Stormcloaks during the Civil War) can be confronted directly regarding the subject. Also if the dragonborn use a Shout in the presence of a guard (using Whirlwind Sprint or Unrelenting force are confirmed) they will make him talk to the dragonborn to stop it, after which talk to him and can ask him about the fire.

NOTE: The dragonborn may have to "enter" the burned down house, in order for the innkeeper to have the dialogue option to speak with the Jarl.

Objectives

 * Talk to the Jarl
 * Investigate the Burned House
 * Find Helgi after dark
 * Talk to Thonnir
 * Investigate Alva's House
 * Show Alva's Journal to the Jarl
 * Kill the Master Vampire
 * Return to the Jarl

Talk to the Jarl
When asked about the burned down house, the Jarl will indicate that the house had once belonged to Hroggar and that one night the house had burned down while he was away. Unfortunately, Hroggar's wife and daughter, Helgi, had perished in the blaze and rumors around town cite that Hroggar had set the blaze himself so that he could be with another woman, Alva. The Jarl wishes to know what really happened, accident or murder.

Investigate the Burned House
Upon entering the burned out house, Helgi's ghost will be waiting in the corner. She recounts what little she knows but promises to reveal more after a game of hide and seek. She wants to wait until nightfall however, as "the other one" will be playing too and only comes out at night.

Find Helgi After Dark
Helgi, or rather her grave and coffin, can be found west of town. The Jarl reveals the location if the Dragonborn asks about it. (It may not be marked on the map until the player gets close to it) However, it has been exumed by Laelette, the missing wife of Thonnir. Laelette will attack when approached and is in fact a Vampire. Once Laelette is dead, Helgi will explain from within her coffin that Laelette was supposed to burn her and her mother, but had a change of heart and tried to turn Helgi beforehand and keep her forever. Although Helgi had felt the cold kiss of Vampirism, it is likely that Laelette had not waited long enough and the fire had killed Helgi regardless. Though, it said in Alva's Journal, that she never knew how to "Turn" anyone properly.

Ask Thonnir about Laelette
Thonnir will likely happen upon the grisly scene and be hysterical at the sight of his dead vampire wife. When asked about the circumstances of Laelette's disappearance, Thonnir will state that he had believed that she had run off to join the Stormcloak rebellion. Though he also remembers that she had been spending a lot of time with Alva who, just the week prior, Laelette despised. In fact, she was supposed to meet Alva the night of her disappearance but Alva had said she never showed up. Given the circumstances, it is presumable that Alva is in fact a vampire as well.

Investigate Alva's House
Hroggar is staying in Alva's house and will likely be there upon arrival. He will be immediately aggressive so a high sneak skill, invisibility, a calming spell or some other such tactic may be employed if an armed confrontation is to be avoided. Alva's coffin can be found in the basement and in it, Alva's Journal. Alva may or may not be present depending on whether it is day or night. The journal goes into great detail of her plans and reveals that Movarth, a master vampire, plans on turning the town into what equates to blood farm for his coven of vampires.

Show Alva's journal to the Jarl
Returning to the Jarl with the journal will prompt her to ask that the master vampire be dealt with so such an awful fate not befall Morthal.

Kill the Master Vampire
Upon leaving Highmoon Hall, a mob with Thonnir in the lead has assembled to assist in taking retribution on the Vampires. Travel northeast to Movarth's Lair where Movarth Piquine lies in wait. The townsfolk can either be told to stay, as they will likely die, or Thonnir may come. Vampire Thralls serve as guardians to the small coven of vampires. Movarth can be found sitting at a large banquet table, counting coin and living large. If you are struggling to kill the Master Vampire, you can retreat through the cave. There is a point where the Master Vampire and his Thralls do not go past - the room with the dead Nord and Redguard in an open grave is safe. You can use this point to retreat, wait and heal yourself. Be aware that the Nord, Redguard, and Vampire Thralls (once killed) can sometimes be brought back to life temporarily by Movarth or the Thralls and will start attacking you.

If you have a high sneaking level you can sneak up on the left when entering the cave where Movarth sits. From up there, you can shoot him and the Vampire Thrall with a bow. They won't find you.

Return to Morthal's Jarl
Once Movarth has been dispatched and his coven eradicated, return to the Jarl for a reward. In addition to the gold, the Jarl will offer the title of Thane of Hjaalmarch provided three people in the hold are assisted with their troubles (if you completed The Battle for Fort Snowhawk, the title will already be available to you).

Notes and References

 * If both Alva and Hroggar were killed during the break in, stealing from their house, even without witnesses, can earn a visit from Hired Thugs with a contract put out by dead Hroggar.
 * If Alva is killed but Hroggar is left alive during the break in, subsequent attempts to speak with Hroggar will cause him to become outraged at the Dragonborn and immediately attack.
 * It is possible for both Alva and Hroggar to survive after completion of the quest. This can be done if the player enters Alva's house at night and wounds Hroggar to the point where he is yielding and kneeling. This will give the player time to swiftly retrieve Alva's diary in the next room and exit the house thereafter. Hroggar shouldn't pursue the player outside. He will be non-hostile and he'll even thank the player once the quest is successfully completed, even though Alva will still be living in the same house.
 * It is possible to take the journal whilst leaving Alva alive, for example by using "Voice of the Emperor." She will stand in Morthal until the journal is handed to the Jarl, after which she will run to Movarth's Lair and either take sides with the vampires there or be killed by them. It seems Hroggar will thank you and remain non-hostile as long as Alva did not die at your hands during the penultimate stage of the quest.
 * If you enter Alva's house before you assault Movarth's Lair and during the day, she might be in her coffin in the cellar. If your sneak skill is high enough, you can kill her in her coffin before she attacks. You can then take her Tavern Clothes, which are rare.
 * If Benor is your follower during this quest he will still join the mob. He will join you again after the sequence outside Movarth's Lair. If you enter Movarth's Lair before talking to the mob outside, he will not follow you. You will have to exit the lair and speak to the people of the mob before he will follow you.
 * If you speak to Thonnir outside Movarth's Lair, the dialog will give you the option of having him join you (and your follower, if you have one with you) in the assault on the lair. The other members of the mob return home.
 * There is a chance to upgrade the Ebony Blade in this quest. Simply sell some firewood to Hroggar before breaking into Alva's house and then kill him with the Ebony Blade.

Bugs

 * Sometimes Helgi will not speak to you after killing Laelette or when you activate her coffin. (on the Xbox 360 at least, the quest is still able to be completed once all other stages are done, and you will still receive your reward from the Jarl). To avoid this, you must activate Helgi's coffin immediately after killing Laelette and before Thonnir reaches his late wife's corpse, which forcibly progresses to the next part of the quest.
 * After killing Laelette, she may get up and start walking in place. She can still be searched and she is still considered dead. She also will not attack.
 * Laelette may not turn hostile, and she doesn't even respond when you try to talk to her.
 * If Movarth is killed before the mob reaches the outside of the dungeon (and has a small dialogue in which they nominate the Dragonborn to go in) the mob will remain at the entrance to the dungeon.
 * Alva may turn hostile if a conversation is attempted, and attack the player as any other vampire would (and can possibly be aided by Hroggar if close to the house). Even if in self-defense, retaliating and/or killing her will still count as a murder and incur a bounty.
 * When leaving the cave after killing Movarth, the ghost of Helgi will begin to speak, but occasionally she may disappear and her dialogue will be cut off. This is probably a similar bug to the one that affects Esbern.
 * If you choose to let Thonnir follow you in the cave, then abandon that quest, he will continue to follow. This makes it difficult to steal/kill, since a bug may occur in which he wont leave your service until the quest is complete.
 * When arriving in Morthal for the first time, after the Empire has taken over Skyrim, Idgrod Ravencrone may not give this quest. Instead, the player must get the quest from the innkeeper, then talk to the Jarl as per quest objectives.
 * If you break into Alva's house and kill her before prompting the investigation of her house, Alva's journal may not appear.
 *  When entering the cellar of Alva's House, a bug might occur in which portions of the floor are missing and replace with a green background color. Objects near the missing floor, such as baskets, might fall into the green section of missing floor, disappear, respawn and fall into the green section of missing floor repeatedly. If the player walks onto a section of the floor that is missing, they may slowly sink beneath the floor to the point where he or she is viewing the cellar from beneath the floor. Walking back onto a section of the floor that is not missing should allow the user to rise above the floor once again. Exiting the cellar and entering again might keep the bug from reoccurring.
 * Sometimes, if you enter the cave before speaking with the mob and then proceed to kill Movarth and finish the quest, the mob members will completely disappear from the game. Movarth's Lair will also consistantly have all its people revived after each visit inside. So far, there hasn't been a method found to fix this problem except to go back to a previous save.