Obtaining the access key to the second part of the sewers | Mission 7 - The Flooded District Dishonored Guide
Last update: 11 May 2016
New Main Quest: Get the Sewer Master Key from Granny
After you enter the cave, you will meet Granny Rags and you will find out that she managed to catch Slackjaw (the leader of the gang, for whom you might have already performed some missions), whom she intends to murder and make into a stew. There are several variants for you to choose from. The suggested variants have been described below.
Variant 1; Quickly, obtain the key) If you don't want to lose your time over resolving the conflict between the Granny and Slackjaw, you may just focus on getting the Dunwall sewer master key really quickly. To do that, you need to rob the Granny, but you need to know that you will be caught red handed even if you've used sneak mode and hold time. The important piece of information here, is that you leave as soon as possible after you steal the key (more about this in the subsection entitled Summary).
Variant 2; Cooperate with the Granny) If you want to play along, so that she gives you the key of her own volition, you need to initiate a conversation with her and confirm that you want to cooperate and kill Slackjaw.
New Optional Quest: Incapacitate Slackjaw
Approach the imprisoned Slackjaw and use your blade, or your pistol, to kill him.
New Optional Quest: Get Granny's key
New Optional Quest: Unlock Slackjaw
Approach Granny and take the Dunwall sewer master key). In theory, you could already leave the place already but, if you want to keep her company, act in accordance with Granny's wish, return to the dead Slackjaw and pull the lever on the left to release his corpse.
New Optional Quest: Put Slackjaw in the tub
New Optional Quest: Talk to Granny
New Optional Quest: Get your gift from Granny
Approach the dead Slackjaw and lift the corpse. Carry the body over to the tub, shown in the above screenshot, and put him in. The only remaining thing to do here, is talk to Granny to learn about a reward for your deed. (the whereabouts of the reward is described in the subsection entitled Summary).
Variant 3; cooperate with Slackjaw) If you want to rescue Slackjaw from certain death on the hands of the Granny, it is a good idea to initiate a conversation with him, and confirm that you indeed want to help him. It is worth pointing out here that it is a way better variant than the previous one because nobody (neither Slackjaw nor Granny) will have to die.
New Optional Quest: Find Granny's cameo
Start the same way as in the case of variant 1, i.e. by robbing Granny of the Dunwall sewer master key. The next step is less obvious, because you need to find the only physical object connected with Granny, so you can get rid of her once and for all. Notice, at the same time, that Granny has sent rats to get you, so you need to remain in motion for the whole time.
Go now to a shack located on a higher level of the cave. The object that you are after, is the pillow shown in the above screenshot.
New Optional Quest: Destroy Granny's cameo in the furnace
Right after you collect Granny's pillow, you need to perform the following activities, thanks to which the rats won't manage to get you. Turn around to face the furnace and use to lever to the left to open it, toss the pillow inside (the upper-right dialogue option - the above screenshot), and pull on the lever to the left again.
New Optional Quest: Defeat Granny one last time
It's not the end, yet. You need to deal with Granny for good, now. She started to teleport all around the cave. The good piece of news is that the game does not make you kill her. The best method, therefore, is using sleeping bolts (the above screenshot), or holding time combined with choking Granny.
New Optional Quest: Unlock Slackjaw
Before you leave (more about it in the subsection entitled Summary), make sure that you have the sewer key on you, and use it to free Slackjaw. As a means of rewarding you, the bandit leader will give you large amounts of gold.
New Main Quest: Return to the Sewer Gate
Summary) Regardless of how you chose to resolve the conflict between Slackjaw and Granny, it would be a good idea to have a look around the entire cave. In the cave there are gold, food, Sokolov's health elixir, two Piero's spiritual remedies, sleeping bolts, three books and a Sokolov's painting.
Finally, inside Granny's shack, there's door that can be opened with the sewer key. Search the place for gold, ammo, bolts and a rune (the above screenshot). It is worth adding that you can collect the rune even if you haven't cooperated with Granny.
To leave this location, you need to smash the boards shown in the above screenshot, jump into water and wait for the current to take you an area in the sewers that you visited earlier.