A Cornered Rat is the second main-quest of the second Skyrim act.
A Cornered Rat starts during your dialogue with Delphine, after the quest called Diplomatic Immunity.
During this quest, you will have to visit the following locations: Riften, The Bee and Barb, The Ragged Flagon, The Ratway, The Ratway Vaults, The Ratway Warrens, Riftweald Manor, Riverwood and Sleeping Giant Inn.
Some of the characters you will interact with are Brand-Shei, Brynjolf, Delphine, Esbern, Keerava, Madesi, Salvianus and Vekel the Man.
The quests story continues the events started in the first main-quest. Delphine wants you to find her contact in Riften, a character named Brynjolf. According to Delphine, Brynjolf can offer additional information regarding Esbern and his exact location.
Since the Thalmor guards also want to find Esbern, you have to move quickly and travel to Riften.
Objective 1: Talk to Brynjolf
When you talk to Delphine, you can ask her additional questions regarding the Thalmor and the Blades.
You will find out that, Brynjolf is a member of the Thieves Guild and that the Thalmor hunted the Blades after the war because of the White-Gold Concordat, which was signed with the Empire.
When you are ready to go, make sure you pick up your equipment and travel to Riften.
When you reach Riften, you will be stopped at the gates by a guard, who asks you to pay a small tax of 10 gold.
At this point, you can opt to persuade, intimidate or pay the guard. All these options have the same effect, and you will be able to enter the city.
It is not a good idea to kill the guard, because you will end up in jail, sooner or later.
Go to Grand Plaza or inside the Bee and Barb and a strange character will interact with you. He is Delphines contact: Brynjolf.
NOTE: Depending on how you have played until now, you have several options to find Esberns location. If you meet Brynjolf for the first time, and you didnt attack the guard at the gates, you will notice that Brynjolf has a quest for you, called A Chance Arrangement.
If you want to find where Esbern is, you must complete this quest; however if you persuade Brynjolf he will eventually tell you the location of Esbern. If you already completed A Chance Arrangement, then Brynjolf will help you immediately.
No matter how you decide to approach Brynjolf, you will find out that Brynjolfs organization had some bad luck lately, but if you want, there are additional tasks to be completed.
He also tells you that if you are interested you can find him at the Ragged Flagon tavern, in Riften’s Ratway. Esbern is also in the Ratway.
Objective 2: Search the Ratway for Esberns hideout
Get near the waters edge and look for a barred gate that allows you to enter the sewers.
In the first tunnel, you will meet Drahff and Hewnon Black-Skeever who will try to rob you. If you wish to avoid a fight, persuade Drahff and tell him that, you have killed dozens like him. If not, you can kill both of them and advance.
Proceed through the tunnels but pay attention to the environment because there is a bear trap ahead and several oil traps.
When, you finally reach the tavern, locate the bar and you will see that Brynjolf is talking to Vekel the Man, the bartender.
To advance, you should also talk to Vekel or you can search for Dirge, another character that can tell you more about Esbern. In both cases, ask Vekel or Dirge about an old guy, hiding out, and you will notice that both characters must be persuaded, bribed or brawled.
The choice is yours, and no matter how you act, the effect is the same. You will find out that Esbern hides in the Ratway Warrens.
NOTE: If you completed the tasks for the Thieves Guild and you have the quest called Loud and Clear active, Vekel and Dirge will show you the way to Ratway Warrens.
Objective 3: Find Esbern in the Ratway Warrens
NOTE: At this point, it is possible for you to meet Gissur, if you spared his life in the previous main-quest. During your dialogue with Vekel or Dirge, Gissur will hear what you say and sneak out to inform the Thalmor Guards. If you wish you can kill him, or you can hide and watch how the Thalmor Guards confront the thieves. Additionally, you can reveal your presence and slaughter all guards and Gissur. Another character that may appear is a Khajiit assassin named Shavari who was hired by Elenwen to hunt you down. When you reach the tavern, look around and kill the Khajiit that is following you. Make sure you loot Shavaris corpse because he carries a note from Elenwen.
On your way to the Ratway Vaults, you will encounter several Thalmor Guards. You can avoid some fights if your sneaking skill is above average, or you can directly attack and slaughter your opponents.
The entrance to the Ratway Vaults is marked by a wooden door and behind it; you will encounter several unusual characters (most of them are crazy).
Make sure you locate the locked door in the southwest corner, up on a balcony. That is your target.
Avoid Hefid the Deaf, Knjakr and Salvianus because they will get hostile when they see you.
When you reach the door, activate it and you will hear a voice telling you to go way.
Talk to the character behind the door and mention the following words: remember the 30th of Frostfall (as Delphine instructed you).
If you didnt talk to Delphine after the previous quest, just tell the old man that you are the Dragonborn.
The strange character will tell you that he is Esbern and he opens the door.
Objective 4: Talk to Esbern
During your dialogue with Esbern, you will find that Alduin has returned and that the end of the world is near (according to him).
At this point, you will start the third main-quest: Alduins Wall.
