Short summary: The first quest of the Old Ebonheart Fighters’ Guild. The player must find a way to remove the witch's curse that's been cast on Foedus Locutius, a guild quest giver. The player seeks out the witch and forces/persuades her to help. Turns out that Foedus is not cursed, but possessed by a minor Daedric entity which the player has to fight. The player will also have to make a choice whether or not to kill the witch.
Looong description: Rathys Madalvel, a scout in the Old Ebonheart Fighters' Guild, tells the player that normally new chapter members get their jobs from Foedus Locutius. However, Locutius hasn't been his normal self ever since he returned back from his mission successful to kill the witch Margia Sycora (to be created and placed in Manumnabi). The once relatively mild-mannered warrior has been reduced to a madman spewing obscenities at anyone who goes near him. It is evident that Locutius has been cursed by the witch with her dying breath. Rathys says that the player should go get a Restore Willpower Potion and have Locutius drink it. It is likely a simple potion alone will not cure him, but perhaps it would provide a moment of clarity for Locutius so he could be questioned for clues on how to permanently lift the curse. Rathys Madalvel gives the player a little money to buy the potion and wishes them good luck before heading out himself: he says he's almost constantly on the road – delivering messages between Old Ebonheart, Narsis, and other guild chapters.
Talking to Locutius without a Restore Willpower Potion will result in him unleashing a barrage of pseudo-Shakespearean insults upon the player (”What are you ogling at, you arse-faced goat? Your unsightly mug must be the reason why there aren't any mirrors left in this damn elf-infested sinkhole of a province!” – that sort of thing). Giving Locutius a potion will help him to get a hold of himself for a moment and he manages to admit to the player that he wasn't able to kill Margia Sycora even though everyone thinks he did. Instead the witch put a curse on him and Locutius says he barely made it back alive. Before the madness begins to take over Locutius tells the player where to find Margia Sycora and asks the player to make her lift the curse. Then Locutius starts insulting the player again.
Player finds the witch. (Use the cave interior "Manumnabi" located in cell 6, -21/-22 ) Margia Sycora is not happy to meet another Fighters' Guild member as the last one tried to kill her. He explains to the player that she is not a witch, but in fact a cultist of the Daedra Lord Vaermina. She has no idea why anyone would think that she was a witch that needed to be killed. She also reveals that Foedus Locutius isn't cursed. He's possessed by a lesser Daedric being that's speaking with his mouth. The player asks Margia Sycora for help. She is of course reluctant to do anything for the man who tried to kill her. After some persuasion she'll agree to help on one condition: she wants the name of the person who contracted the Guild to kill her. The player doesn't know this, but they can promise to get the information from Locutius once he's back to normal. Margia Sycora is doubtful whether or not the player can be trusted, but accepts. She admits that she isn't quite sure how to drive away the Daedra inside Locutius. The summoning incantation she used she had never used before (”When one is attacked by an armor-clad madman waving a sword, one tends to panic”). Margia Sycora suspects that there's no ”reversal spell” per se. Instead she brews a special potion she thinks might force the Daedra out, but it would still have to be killed to banish it back to Oblivion. She warns the player that the Daedra is bound to be angry when driven out. She gives the potion to the player, and reminds them about their agreement: after the Daedra has been dealt with she wants to know who ordered her killing. [Optional: Player can kill Margia Sycora after getting the potion; the Guild was paid to kill her after all]
The player returns to Old Ebonheart and gives the potion to Foedus Locutius who drinks it and becomes paralyzed for a moment. A unique Vermai, Vhal'baan, will appear. The Vermai will be angry and curse at the player before attacking them. The fight shouldn't be too difficult – there are, after all, other Guild members to assist the player. After Vhal'baan has been killed the player talks with Foedus Locutius who's getting used to having the control of his voice back. Locutius thanks and rewards the player. He says that he trusts that the player also took care of Margia Sycora. If the player didn't kill Sycora they can either lie or tell the truth. Foedus will send the player to finish the job (”it might not feel like the right thing to do, but business is business”) if Sycora is still alive – Foedus is a bit angry about being possessed. If the player informs Foedus that Sycora is not a witch but a cultist of Vaermina, Foedus simply shrugs saying that he is not interested in semantics. The player can try asking Foedus about the person who contracted the Guild on this job. Foedus doesn't like the player asking about their clients, but says he doesn't know the answer. He tells the player that Rathys Madalvel got the OE chapter this contract: it's likely someone from Narsis.
If she's still alive the player returns to Margia Sycora. She'll be unhappy to hear that the player doesn't have the exact name of the person who wanted her dead. She'll be even less happy to hear that the Guild is still after her – even after she helped to cure Foedus Locutius. Sardonically she gives the player a broomstick telling them to show it to (”that fool”) Locutius as a proof that the ”witch is dead”. The player can agree to this plan or decide to kill her (“You ungrateful, small-minded, maggot-eating bastard!”). Locutius will be none the wiser either way.
After the quest is finished Rathys Madalvel can be found at the guildhall once again. The player can ask him directly about the contract on Margia Sycora. He isn't at all irritated by the question. Rathys says that Foedus is mistaken to think that the contract came from Narsis. Rathys explains that a messenger working for Draler Ilvi – the Indoril lord of Roa Dyr – gave him a letter contracting the Guild to kill Sycora. [Though this only a minor detail: The real client is of course in Narsis: the Camonna Tong. The particular reason for them to want Sycora dead might have something to do with the Skull of Corruption (a relic of Vaermina's) and the Thieves Guild (in possession of the skull, quite literally). Shifting the ”blame” on House Indoril is something that works for the Tong.]