1. Reach the forge
- Get the Hammer from the sewer pipe route below the large hall.
- From the hall, descend the basement stairs by the large doors.
- Smash the rusty gate and explore the rooms until you reach the Big Smelter.
- Collect Coal, Scrap Metal and the larger casting mold from the nearby forge rooms.
2. Forge the two keys you'll need
- Use the mold already on the Big Smelter to cast the key for the side room. Supply 5 Coal below + 8 Scrap Metal above, then pull the lever.
- Pick up that key and set it aside.
- Carry the larger mold to the smelter, fit it and repeat with another 5 Coal + 8 Scrap Metal.
- Use this second key on the oversized basement lock.
Keep the forged keys separate: the original mold opens the side room beside the Jaguar Door, and the larger mold opens the oversized basement lock. See the forge walkthrough.
3. Open the skeleton-guarded chest
- Go through the unlocked basement doorway toward the Jaguar Door, the door showing three Key Piece sockets.
- At the Jaguar Door, turn right rather than trying to forge all three Jaguar pieces now.
- Unlock the right-hand side room with the key made from the initially fitted mold.
- Defeat or avoid the skeletons in the room and reach the chest at the far end.
- Open the chest and take the Prison Key. Return to the large hall.
4. Find the prison entrance and use the key
- From the hall, go upstairs and follow the left-hand cave route to a chest with a Small Key.
- Return upstairs, take the left path and find the large wooden plank.
- Move the plank across the gap to create a bridge, then cross it.
- Unlock the first door with the Small Key and descend the spiral staircase.
- Equip a lit Torch in your right hand and burn the webs covering the passage.
- Use the Prison Key on the barred inner door.
5. If you're standing at a locked door with the wrong key
| Blocker | Missing item or action |
|---|---|
| Oversized basement keyhole | Key from the large forge mold |
| Skeleton room right of Jaguar Door | Key from the forge's original mold |
| First door beyond the plank bridge | Small Key from the upper cave chest |
| Webs down the spiral stairs | Torch in right hand |
| Barred prison door after the webs | Prison Key from skeleton-room chest |
Once inside the prison, use the Pickaxe guide for the lower stairway, or the early walkthrough for the lever and cell-switch sequence.