Missing in Action

Missing in Action is a quest available in.

Background
"Fralia Gray-Mane in Whiterun is convinced that her missing son, Thorald Gray-Mane, is still alive and being held captive. She asked me to visit her home to speak privately about the matter."

Objectives

 * 1) Meet Fralia in her home
 * 2) Find evidence of Thorald's fate
 * 3) Deliver proof to Avulstein
 * 4) One of two options:
 * 5) *Meet Avulstein at Northwatch Keep
 * 6) *Find a way to release Thorald from Thalmor custody
 * 7) Rescue Thorald from Northwatch Keep
 * 8) Lead Thorald to safety
 * 9) Speak to Thorald
 * 10) Return to Fralia Gray-Mane

Walkthrough
The quest can be started in two ways. The first is by speaking to Fralia Gray-Mane in Whiterun. She will tell the Dragonborn that her son is missing, but alive, regardless of what anybody says, and that she would like to discuss it in private at her home. Once there, Thorald's brother Avulstein will explain the situation further. Alternately, the quest can be started by talking to Avulstein directly. Either way, Avulstein explains that they would like any proof that Thorald is indeed alive, and they want him found.

Find the evidence
There are a few ways to go about getting proof from the Battle-Borns. The most direct is to sneak into their house (the back door is unlocked for this purpose) and find the book Imperial Missive on the desk. The book is located behind a locked door. It will state that Thorald has been taken prisoner by the Thalmor, and relocated to Northwatch Keep.

Instead of stealing the evidence from the Battle-Born house, the Dragonborn can try confronting Jon Battle-Born with knowledge of his tryst with Olfina. To do so, first pickpocket him for a letter from Olfina. After bringing it up with him, Jon will agree to bring the Imperial missive to the Dragonborn at the Statue of Talos.

It is also possible to persuade Idolaf Battle-Born into giving the information, but it requires a high Speech level (confirmed level 90 without perks or fortifying equipment on PS3, confirmed 75 or above on PC).

The third, and easiest, option is to speak with the child Lars Battle-Born. With a little convincing, he divulges that the child-orphan Braith is bullying him, and he asks for help with the situation. You can speak with Braith and convince her to stop, making you a friend to Clan Battle-Born. You can then enter the study (requires picking an Adept lock) and take the missive.

Rescue Thorald
With the knowledge of Thorald's location, the Dragonborn can choose to relay it to Avulstein and join his group in attacking the fort, or simply go alone. Head to Northwatch Keep.

Note that there is an unmarked quest objective, Find a Way to Release Thorald From Custody, and the option to do so is available, but one must first have completed the quest "The Jagged Crown" for the Imperial Legion to open up the dialogue to do so. If one chooses to find another way to free Thorald, General Tullius will give an Imperial missive stating the release of Thorald into the Dragonborn's custody. If the Dragonborn then speaks to the front guard of Northwatch Keep and tells him that they have come for Thorald, the guard will refuse to confirm whether they hold a prisoner by that name, and say that a prisoner can only be freed by order of the Imperial Legion.

Once at Northwatch Keep, the Dragonborn can fight through waves of Thalmor guards throughout the fort to find Thorald. The guards use shock spells, and leveled weapons and armor. Alternately, there is a side entrance protected by a single guard and a Master-level lock that can be picked. This will make the trek through the Keep much easier, requiring only a fight through a single room with a few enemies.

Proceed through the Keep to the prison area. Thorald Gray-Mane is chained to the wall in the back of the room. Kill the Northwatch Interrogator to free him. He will grab a nearby weapon to help protect himself before following the Dragonborn.

After exiting, Thorald will thank the Dragonborn for saving him. He will then explain that it is not safe for him to return to Whiterun, as the Thalmor will be after him now. He states that he will join the ranks of the Stormcloaks to blend in, and gives the Dragonborn a message to pass on to Thorald's mother: "Suffer the winter's cold wind, for it bears aloft next summer's seeds." He then parts ways.

Return to Fralia
Once the Dragonborn approaches Fralia with the news of her son's survival, she will ask for proof. Give her Thorald's message. She will give thanks for bringing her the peace of knowing that her son is alive and safe, and not locked up in a prison cell. She then rewards the Dragonborn with a random Skyforged weapon or an enchanted steel weapon, originally intended for Thorald, and the quest is complete.

If Fralia's husband, Eorlund, has died anytime before the conclusion of this quest, Fralia will say that she does not have much to offer, due to the passing of Eorlund, and will be able to give 200 instead of the weapon.

Trivia

 * After completion of this quest, guards will comment "I heard you're the one who gave the Thalmor a black eye. You know how to pick your enemies."
 * Guards will also comment, "I wonder what it's like for those Thalmor, now that they've been taken down a notch..."
 * Vidrald and Geirlund may be found in the courtyard of Northwatch Keep after the quest is completed.
 * Stealing the evidence may cause Bergritte Battle-Born to send hired thugs after the Dragonborn, even if he or she were not caught in the act.
 * Joining the Thalmor with console command by typing  does not make the guard friendly to you.
 * Although you can make them friendly by killing them, tweak their factions to player ally, remove Thalmor faction, set relationship rank 4, and resurrect them afterward.

Bugs
Der Vermisste Без вести пропавший