Received from: Varric [Lowtown - The Hanged Man]
Step 1: Find the Grey Warden
You will automatically receive this task from Varric during the conversation during the A Business Discussion main quest #1 (M15, 2). Your task in this quest is to find the Grey Warden and ask him to join your expedition to Deep Roads. Go out of the inn and during daylight head to [Lowtown - Lirene's Ferelden Imports]. The entrance can be found on the bazaar #2 (M12, 2).
Inside the shop, search for Lirene #1 (M14, 5). During the conversation, choose the upper dialogue option #2 to ask her about the whereabouts of the Grey Warden. Irrespectively of the course of the conversation, you will learn that he's inside the clinic in Darktown.
I'd recommend saving your game now, as once you exit the shop you will be accosted by a group of deserters, who won't like that you're searching for the Grey Warden (M12, 8). You can react in two ways:
- peaceful option: ask Bethany or Carver to join in (middle left dialogue option) or convince the refugees about your good intents (lower left dialogue option) #1
- aggressive option: choosing whichever right dialogue option (upper, middle or lower) will lead to a fight with the refugees #2
If you have chosen the peaceful option, you will be able to continue the game at once. In the other case, you will have to eliminate the group of Deserters #1 and Deserter Archers. The enemies won't be too hard, but nevertheless you should keep an eye on your health level and eliminate the archers in the first place. Irrespectively from whether you fought the deserters or not, leave this area and head to [Darktown]. After you get there, head east #2.
Stay alert, as on your way you will be attacked by Looters and Mercenaries #1 and they won't be only warriors, but also archers and rogues. Especially look out for the last ones and don't let them use surprise attacks. After getting to the eastern part of the Darktown, turn to the north #2.
Step 2: Convincing the Grey Warden to cooperate
You have to get to the next area and open the door in the front #1 (M23, 5) leading to [Darktown - Ander's Clinic]. A conversation with the Grey Warden Anders will automatically begin. Unfortunately you won't have any influence on it. Anders cannot be bribed or cow into giving the maps needed for The Deep Roads Expedition. The only way is to offer help in freeing Karl, who's being held by the Templars #2. It's worth to add that during the conversation with Anders you might be asked for your opinion of the mage's rights. I'd suggest choosing the answers carefully, so that you won't offend any mages in your party.
Step 3: Finding Karl
You can now leave this area and during the night head to [Hightown]. Anders can be found nearby the entrance to the Order in the western part of the area #1 (M4, 7). Confirm the will to begin the action and you will be automatically moved to [Hightown - Chantry] (M8, 1). Go forward and then turn to the right #2. Use the stairs to reach the upper balconies.
Check one of the northern rooms and you should find Karl #1 (M8, 2). Try to talk with him and it will turn out that he's undergone so called tranquility. It's not the end of trouble, as Templars will appear #2. You will have to fight them and you will also learn Ander's secret.
Step 4: Defeating the Templars
Start by attacking the Templars and Templar Archers #1, who should die rather quick. You shouldn't also worry about Anders, as you won't control him. Stay alert, as pretty soon a Templar Hunter will enter the scene #2. Take care of him quick, as his surprise attacks might cause large damage.
In the end take care of the Templar Lieutenant #1, as he's considerably stronger than his colleagues. Right after the fight a cutscene will start, during which Karl will regain consciousness for a moment and ask Anders to execute him. Irrespectively of the chosen dialogue option #2 the execution will happen.
Step 5: Talking with Anders
After finishing the affairs at the Order, you will be automatically moved back to [Darktown - Ander's Clinic] #1 (M23, 2). You can ask the Grey Warden about the Spirit of Justice and make foundations for a new affair #2. Irrespectively of the chosen dialogue options, Ander will give you the Deep Roads map (needed for The Deep Roads Expedition) and will join your party for good. You will also unlock a new quest.
Companion quest unlocked: Questions and Answers