The Forsworn Conspiracy

Objectives

 * Read Eltrys' Note
 * Go to the Shrine of Talos
 * Find evidence about Margret
 * Find evidence about Weylin
 * (Optional) Talk to Margret
 * (Optional) Obtain the key to Margret's room
 * Read Margret's Journal
 * Find evidence about Thonar
 * (Optional) Obtain the key to Weylin's room
 * Read Weylin's Note
 * Find out who “N” is
 * Find evidence about Nepos
 * Return to Eltrys

Quick Walkthrough

 * 1) Witness Weylin's attack against Margret upon entering Markarth.
 * 2) Meet Eltrys inside the Shrine of Talos
 * 3) Investigate Margret’s room at the Silver Blood Inn
 * 4) Investigate Weylin’s room in The Warrens
 * 5) Head to the Treasury House and talk to Rhiada
 * 6) Speak to Thonar inside the Treasury House
 * 7) Go to Nepos' House and speak to Nepos
 * 8) Return to Eltrys

Walkthrough
Upon first entering Markarth, the Dragonborn is witness to an argument in the market. After a man called Weylin shouts something about the Forsworn, he attempts to kill a woman named Margret, either failing or succeeding his attempt depending on if the Dragonborn intervenes. At the moment that the attacker draws his weapon, the Markarth City Guards rush towards the attacker and slay him. Afterwards, a man named Eltrys approaches the Dragonborn and hands the Dragonborn a note asking to meet him in the Shrine of Talos.

It is possible to save Margret in the market. There is no significant difference to the plot between saving Margret or allowing Weylin to kill her, although if Margret is saved, she rewards the Dragonborn with a Silver Emerald Necklace. The way of gathering information about Margret changes, as do some dialogues, but the rest of the quest remains the same.

Go to the Shrine of Talos
At the Shrine of Talos, Eltrys explains that his father was killed by the Forsworn and that he has been trying his whole life to find out why. He asks the Dragonborn to investigate Margret's background at the Silver Blood Inn and Weylin's room in The Warrens.

Silver Blood Inn - Margret 's room
If Margret is dead, and the Dragonborn obtained Margret's room key from her body, the room can be approached directly. Otherwise the Dragonborn must ask the bar-keeper Kleppr about Margret. The Dragonborn can also speak to his daughter, rent the room for 10 gold, bribe, intimidate, persuade, or pickpocket Kleppr to get the key. Margret's Journal is inside her room in the end table next to the bed. Reading it will update the quest log. The journal mentions Thonar Silver-Blood, and the next objective becomes "Find evidence about Thonar."

If Margret is alive, she will be seated by the fireplace. She can be persuaded or intimidated, revealing that she is an Imperial investigator. She mentions Thonar Silver-Blood, which also activates the objective, "Find evidence about Thonar."

The Warrens - Weylin 's room
Head down to The Warrens, and talk to Garvey. Garvey can be bribed, intimidated, or persuaded to hand the key over. Weylin's room is the last one on the right side. Look into the chest and find Weylin's Note signed with the letter "N." The player will have to find out who this mysterious "N" is. When the Dragonborn exits The Warrens, Dryston, a mercenary, will approach stating that the investigation has gone too far into somebody's business. There is no option to avoid the brawl; defeat Dryston, and he confesses that he was sent by Nepos the Nose, or "N." The quest log updates to finding evidence about Nepos.

If the player is wearing any sort of enchanted armor that does proximity damage (such as the Ebony Mail ), it will cause the guards to attack. Another option is to lose the brawl. Dryston will go to Weylin's room and sit in a chair. With decent sneaking, the Dragonborn can kill him without alarming the Markarth guards. He will drop Dryston's Note, which will update the quest log when it is read.

Upon returning to Eltrys, the player will receive level-dependant amount of gold for both investigating Margret's and Weylin's Rooms. If evidence is discovered about Nepos or Thonar before receiving the reward, the next quest stage will be triggered without receiving the reward.

Find evidence about Thonar
Thonar is located in the Treasury House. Talk to Rhiada, and learn that Thonar doesn't want to be disturbed; although, she can be convinced with persuasion, a bribe, or intimidation. The door can also be opened by lockpicking it. His room is to the left and then straight ahead. Once inside, Thonar is sitting at the table. He'll say something about not wanting visitors. Regardless of the response, he will tell the player character to get out. As soon as the conversation is finished, there is a commotion outside in the main room. Thonar gets up and runs down the hall where there's fighting going on. Thonar's wife is murdered by Nana Ildene, at which point Donnel will join in the attack. The attackers belong to the Forsworn faction, so it's safe to kill them. At this point, talk to Thonar, and he will reveal the truth about Madanach.

Another approach involves pickpocketing Thonar's Journal from him, so his wife doesn't die, and Donnel and Nana Ildene don't attack anyone. The player has to avoid any conversation with Thonar, as this triggers the attack. If the player speaks to Thonar, it is not possible to save his wife; her death is scripted. If the player has a high bounty, Betrid will become hostile towards the Dragonborn and make it impossible to complete the quest. The player can bribe one of the guards by being part of the Thieves Guild or having the speech ability to bribe guards.

Finding evidence about Nepos
Find evidence about Nepos by going to Nepos' house. There the player will be greeted by a woman named Uaile who tells the player to go away; however, Nepos quickly calls from the background and tells her to let the Dragonborn pass. Talk to Nepos and he will reveal that he does not plan to let the player leave the house alive. Make sure to exhaust all dialogue options about Madanach and his plan. After the conversation with Nepos, everyone in the house attacks the player.

An alternative, more silent and safe way, is to quickly pickpocket Nepos' Journal from Nepos (instead of talking to him), and then run outside. If done correctly (without being seen at all after pickpocketing the journal) no one will attack the player.

Return to Eltrys
Return to the Shrine of Talos to meet Eltrys, and find three guards standing over Eltrys' body. One guard says the player has caused a lot of trouble and a lot of work for them. He informs the player that they will pin all the murders and troubles made on the Dragonborn. At this point the player can choose to go quietly or resist arrest. Fighting them will not prevent the next quest, No One Escapes Cidhna Mine, with the exception of shooting them with a bow before any conversation takes place, at which point the quest ends, or the player simply leaves the shrine of Talos and surrenders to the first guard seen.

Additional Tips

 * The killer can also be revealed by pickpocketing Thonar's journal off him (the key to his room can be pickpocketed from the Treasury clerk). This can be done before talking to Eltrys at the shrine. Doing this and entering the shrine spawns the guards there, and allows the player to skip over most of the quest.

Trivia

 * The Cidhna Mine is a quest destination regardless of the Thieves Guild influence of the guards.
 * The Amulet of Articulation, which can be obtained after completing certain Thieves Guild Quests, can be very useful to quickly skip through persuasions. In most stages of the quest there are persuasion options. Since persuasions almost always work with the Amulet, it will save you a lot of time. Alternativly a high speech also works
 * After questioning Thonar Silverblood and then witnessing the murder of his wife, Thonar may compliment Rhiada on her beauty. He will also question her on who she is married to. She explains that just last season she was wed to Eltrys to which Thonar states that Eltrys is a lucky man. From this point in the quest Eltrys will be found dead in the Shrine of Talos.