It seems that Edwinna Elbert at the Ald'ruhnGuild of Mages now wishes, with your assistance, to acquire a book, Chimarvamidium, from a fellow Mages Guild member in Vivec. Chimarvamidium is the sixth volume of Marobar Sul's Ancient Tales of the Dwemer. Evidently Sirilonwe of the Vivec branch has acquired a copy of the book and Edwinna wants you to 'borrow' the book and bring it to her. She warns you that if you are caught stealing you will be expelled from the Guild. Edwinna also provides you with two Scrolls of Ondusi's Unhinging, to use if needed.
Grab your local Guild Guide and head to the Guild of Mages in Vivec. If you haven't been there before, Sirilonwe's quarters can be found down the hall to your left as you leave the Guild Guide teleporter in Vivec (go left, then right). Sirilonwe keeps the copy of the book in a locked (30) chest in her unlocked closet. If you open the locked chest with the closet door closed, you won't get caught. The key to the chest containing the book is on the table sitting next to a locked small chest. Take the book, and head back to Ald'ruhn.
Upon returning to Ald'ruhn, give the book to Edwinna and you are rewarded with a 10 point increase in Disposition with her, as well as a 5 point increase in Faction Reputation.
The VivecGuild of Mages is the only guaranteed location of the book in Morrowind, although other copies can be found as random loot.
If you wish to get a free point in Heavy Armor, read the book prior to relinquishing it to Edwinna.
If you forget, don't worry - Edwinna asks you to return the book as a later duty, so you can read it then.
If you have lost the scrolls or want to keep them, Sirilonwe sells the spell Ondusi's Open Door, which unlocks a 50-point lock on touch.
If you returned the book by mistake to Sirilonwe, it's possible to recover it by killing her, then looting the book. However, be aware that Sirilonwe is involved in other quests.
Each time you refuse to give the book to Edwinna, her disposition drops by 5.