Bianca says Corypheus is getting his red lyrium from the thaig Hawke and Varric discovered years ago on their expedition into the Deep Roads under Kirkwall. It may be possible to reach it using an entrance to the Deep Roads somewhere in the Hinterlands.
Talk to Varric to trigger a cutscene when he is seen speaking in his usual spot to a female dwarf called Bianca. She explains that there is a lead for Corypheus' red lyrium source, as the location of a mine in Valammar has been leaked. Agreeing to help her starts the quest.
Enter Valammar in the Hinterlands with Varric. The fastest way there is fast traveling to Upper Lake Camp. Bianca will be waiting inside Valammar and, after a cutscene, will accompany the group. Head to the lower terrace and let her open the large, stone door that leads to a previously inaccessible area.
Kill the mobs in the room. A codex entry can be found here as well. The key is found in the end of the room, on the desk.
In the following cutscene, it is revealed that Bianca was the leak. She gave the red lyrium mine's key to a corrupted Warden (Larius/Janeka, depending on the choices during Legacy) and therefore unknowingly aided Corypheus.
Return to Skyhold and speak to Varric about what happened.
- 1,025 XP
- 400 Influence
- 3 Power
- When talking to Varric, there is now the option to ask more about Bianca.
- Varric's Tarot Card changes to "The Sun".
- A friendship cutscene for Varric becomes available given a high enough approval.
Open the locked door Edit
- That was handy. - No approval change.
- You were waiting to do that. - Varric Slightly Approves
- There's no time to waste. - No approval change.
Finding the key Edit
Bianca: I just ... wanted to figure it out.
- Did you? - No approval change.
- You're not saying everything. - No approval change.
- That was stupid. - Varric Slightly Approves
Bianca: Then I went to you.
- It isn't really your fault. - Varric Slightly Approves
- You put this on us. - Varric Slightly Approves
- You've done a lot of damage. - Varric Disapproves
Varric: As if i would tell stories about my own mistakes!
- Varric is right. - Varric Slightly Approves
- She's right. - Varric Slightly Approves
- Just let it go. - No approval change.
- Get a room, you two. - No approval change.
Back at Skyhold Edit
Varric: And I am not good at dealing with shit like this.
- Nobody is. - No approval change.
- Talk your way out of it. - Varric Slightly Disapproves
- Just confront it. - No approval change.
Varric: If Cassandra hadn't dragged me here, I'd be in Kirkwall right now, pretending none of this was happening.
- No you wouldn't. - Varric Approves
- Nothing's stopping you. - Varric Slightly Approves
- She did you a favor. - Varric Slightly Disapproves
- If you entered Valammar previously and sealed the tunnel, a new Hurlock alpha will spawn on your return and the Inquisitor will still remark that the hole needs to be sealed even if it already has been.
- If the key to Valammar is obtained for the quest Deep Trouble before Bianca unlocks the entrance to the thaig, the quest may not complete. However if Deep Trouble is started after this quest is resolved, it can be normally completed.