Where the Cellar Key Is and What It Opens
The Cellar Key is beside a body in a side cave near the Wolfsbane Field Lantern in Vale of Wrath, during Chapter 5: Crime. It opens the cellar beneath Mirek's house through the door to the right of the entrance you originally used.
Reach Wolfsbane Field
If you have just started Chapter 5: Crime, speak with James after waking at the Abandoned Church to receive the Outward Pass Key. That key opens the door across the grapple point, to the right of the door leading toward the Caverns. For the Cellar Key route, start from the Wolfsbane Field Lantern in Vale of Wrath.
Prepare Stasis and grenades for the Risen Sapeur miniboss on the cave branch. The enemy is immune to fire, so plan your approach around those other options. Defeating it also earns the Equivalent Exchange Amber.
Follow the Cave Route to the Cellar Key
- Enter the house on the left of the Wolfsbane Field Lantern; this is the house you must pass through to progress.
- Pick up Mirek's Note from the bench on your right as you enter, starting The Lost Boy.
- Destroy the second required weak point along the main route, allowing you to continue toward the shortcut cave.
- Enter the cave containing the shortcut back to the previous area; the room on the right contains the grapple route to the miniboss.
- Grapple up to the platform in that room to reach the miniboss encounter.
- Defeat the Risen Sapeur miniboss to collect the Equivalent Exchange Amber.
- Follow the ramp behind the miniboss's position into the separate cave area.
- Continue past the chest containing a Blade Upgrade Material to reach the body beyond it.
- Collect the Cellar Key beside the body so you can open the cellar back at Mirek's house.
Open Mirek's Cellar and Finish The Lost Boy
- Return through the cave shortcut to the previous area, heading back toward the house where you collected Mirek's Note.
- Locate the door to the right of the entrance you originally used at Mirek's house; this is the door opened by the Cellar Key.
- Interact with the door to unlock it with the Cellar Key and gain access to the cellar.
- Read the note on the table inside to complete The Lost Boy.
- Open the chest in the cellar to collect the Wound that Heals Amber.
Use the Amber from the Cellar
Wound that Heals provides Health regeneration. You can equip Ambers through the levelling menu at a Lantern. Collect the cellar chest during your visit, and remember to read the table note as well: that note completes The Lost Boy.
Find the Correct Locked Door
Use Mirek's Note and the Wolfsbane Field Lantern to identify the house you need to revisit. The Basement Key belongs to the painter's house during In the Name of Art near Under the Bridge, where it opens the door at the back of the first floor. For The Lost Boy, return to Mirek's house and check the door to the right of your original entrance.
Return Later if You Passed the Cellar
The Lost Boy can still be started and completed after the story. Vale of Wrath supports Lantern fast travel, so return to Wolfsbane Field when you want to finish this detour. If you already have the Cellar Key, head back to Mirek's house and read the note inside the cellar to complete the quest.