Innocence Lost

Background
Rumors have been circulating around Skyrim of a child trying to summon the Dark Brotherhood.

Quick Walkthrough

 * Talk to Aventus Aretino.


 * Kill Grelod the Kind.


 * Tell Aventus Aretino that Grelod the Kind has been killed.

Initiating the quest
While venturing around Skyrim, The Dragonborn will begin to hear rumors of a "cursed child." Any innkeeper can be asked about the latest rumors and eventually, the innkeeper will mention that there is a child trying to summon the Dark Brotherhood in Windhelm.

Other ways to initiate
When talking to Idesa Sadri inside Candlehearth Hall in Windhelm, there is the option of asking about a child performing the Black Sacrament.

Idesa can also be overheard talking to Grimvar Cruel-Sea about the child outside the Aretino Residence.

Talking to Maul on your initial entrance to Riften and asking him about Dark Brotherhood rumors will initiate this quest also.

Entering Honorhall Orphanage in Riften and listening to Grelod the Kind will also initiate this quest. After she dismisses the children, The Dragonborn can talk to any of these children, and they will say that they all hate Grelod the Kind, and wish she were dead. They will then ask The Dragonborn to seek out Aventus in Windhelm.

It is also possible to overhear Guards around Windhelm and Riften talk about Aventus, but this will not initiate the quest.

Talk to Aventus Aretino
The child, named Aventus Aretino, can be found inside the Aretino Residence, which has a novice-level lock, and is located near the Grey Quarter in Windhelm.

When first entering the Arentino Residence, Aventus can be found chanting the The Black Sacrament and asking the Night Mother why she has not answered his prayers.

After initiating conversation with Aventus, he will tell you that "He summoned the Dark Brotherhood because his mother died and he was sent to Honorall Orphanage, in Riften. While there, the cruel matron, Grelod the Kind, abused him and the other children, causing him to run away." Aventus believes that the Dragonborn is a Dark Brotherhood assassin, and will ask the Dragonborn to kill Grelod the Kind.

Kill Grelod the Kind
Grelod the Kind can be found in Honorall Orphanage in Riften. Grelod the Kind does not prove any challenge to the Dragonborn. The children at the orphanage will not report you to the Riften Guard. It is advised however to carry out the deed inside Honorhall Orphanage. Be sure not to kill Constance Michel while inside the orphanage, or a bounty of 1000 septims will be encountered.

Once Grelod has been dispatched, return to Aventus in Windhelm.

Reward
Aventus will reward the Dragonborn with the Aretino Family Heirloom which has a base value of 75-100 septims. This will also initiate the next stage of the Dark Brotherhood Questline.

Trivia

 * If The Dragonborn kills Grelod the Kind without ever consulting Aventus Aretino, The Dark Brotherhood will not contact you, initially. If the player meet him after killing the mark Aventus will be very happy ("I knew the Dark Brotherhood were good... but...") but the reward remains the same. The Dark Brotherhood will then contact the Dragonborn.
 * The Dragonborn does not have to talk to anyone prior to talking to Aventus.
 * After completion of the quest, guards in other towns will talk about it. Guards in Riften will add, "Say, didn't I see you coming out of there?"
 * It's interesting to note that all of the guards in Riften will also acknowledge how cruel Grelod was saying something like "the little brats are probably better off". Contrasting, the guards in all other areas (since they didn't know Grelod) will think the murder was a tragedy.
 * Even if the player kills Grelod before accepting his "contract", he will simply think that the "Brotherhood" was so competent, it knew what he wanted done beforehand. Therefore, it is impossible for the Dragonborn to dissuade Aventus from his belief that he/she is a Brotherhood assassin.
 * Aventus' comments before you initiate conversation imply that he has been doing the Black Sacrament for a long time. Later in the quest line, Astrid implies that she knew of his efforts, it seems that she did not believe that the contract was worthwhile, being the only contract in the Dark Brotherhood Questline given by a child.

Bugs
If The Dragonborn kills Grelod before she finishes talking to the kids it may restart the quest to before you talk to Aventus.
 * Sometimes, the door to the orphanage can need a key, but restarting the game can fix this.
 * It is possible for Grelod's corpse to disappear into the floor after she is killed, and reappear in the children's sleeping quarters in the center of the floor.