Under Watchful Eyes walkthrough
Retail evidence: PC Gamer's video-backed route confirms the Stoneward Post back door, stolen keys, and nighttime stealth approach.
Free Mert
- Start Under Watchful Eyes at the Prisoner Processing Camp / Stoneward Post as part of The Firebrand.
- For the low-combat route, buy Shadow Dweller and Dimension Reach in Vampirism before attempting the shortcut.
- Reach Friedo's office, steal the prison keys, and avoid the two-on-one office fight where possible.
- Return at night through Stoneward Post's back door.
- Use the stolen keys to unlock the prison and free Mert.
You can clear the entire fort by force, but the nighttime back-door route reduces the number of soldiers. The task is listed as a three-segment Ambrus activity; confirm the journal cost before committing.
Source: PC Gamer Mert walkthrough and PowerPyx all quests.