The Storage contains many machine parts, including the Trinity Rod and Four-phase Amplitude Rod, which are needed in the Machine Room to activate the Elevator. However, this is not an easy task, as there will be a heavy darkness consuming the area (which makes the Lantern most needed), and many Gatherers wander around the Storage. Daniel even notes that the darkness feels "strange and unnatural," and the player will likely use up a couple of oil bottles in this area. This place is considered to be one of the most dangerous areas in the game.
The flashbacks suggest that this is the place where Daniel's former self stabbed the little girl to death who was trying to escape the castle.
Depending on where you go, a monster will spawn after you pick up a drill part in the room behind the door in the first storage room. Close the door behind you, hide in a shadow so that he is not tempted to break the door, and wait until the music stops, or until you think it is safe.
After you obtain the drill part of the hand drill, go to the second room you can access, which is the chemical storage. Search all the rooms, as there are the handle and the drill turning mechanism in them. The rooms have tinderboxes, and one has a chest containing a tinderbox, laudunum, and an oil jar. Once you get all three drill parts, go into your inventory and use them on each other to create the hand drill. Similar to the refinery, there are unusable wine barrels, and two barrels on the "side" in a frame with a tap on it (they look similar to the oil barrels and are marked as primary and secondary). The tap is rusted shut, so use the hand drill on each barrel and put the chemistry pot from the laboratory in the stream of liquid from the barrels. You will get a pot of explosive liquid. Use this to blow up the rubble blocking you from the rest of the Storage.
The explosives are not on a timer when you set down the pot. What you need to do is set the bomb down, then throw a crate or something at it, then run! It does NOT have a small blast radius, and it can bring you down to the Barely Conscious Healthlevel.
In the room that comes shortly after where you broke the rocks with explosives, there is another room with a table in the middle after you go down a long hallway. There are two doors; one where there are butchered pigs and barrels. In between the barrels is a bottle of oil. If you then go out of that room, turn right, and go forward, there is another door. DO NOT OPEN IT. There is a Grunt lurking behind it.
In the room where a torch turns on by itself, go right and into the next room. Close the door, and pick up the rods. You will hear a grunt growl, so hide in a corner so he doesn't break the door, and wait a minute or two. A Grunt is now wandering around outside. Eventually the monster will go away. (Note: Try not disrupt the chains hanging from the ceiling in the torch room, as they will alert any nearby monsters to your location.)
When it's safe, make your way back to the Back Hall. You will pass the area where you unblocked the caved-in passageway. The Shadow will roar and debris will fall. Don't panic. You need to take care as there is a monster at the top of the stairs after this. When you hear it growl do not go up the stairs any further, and instead, run back and find a dark spot to hide in. Stay there. After a while, when all is clear, head back.You can also run straight past him, as the exit is near and he is not very fast. Get out of there once you have all three rods (including the rod from the Study). Congratulations - you've managed to survive one of the most nerve-wracking rooms in the game!
There is a jammed door in the Storage near the cave-in. There is a trail of blood leading out of that room towards the blocked path. It's highly possible that this is the room where Daniel found the girl. This also may be the place where the Servant Grunt went after looking around the first room, as he is not found in the chemical storage or past the rocks.
As Daniel enters the final area where he actually killed the girl, the fire in the middle of the room will ignite by itself, a terrified cry will be heard, and Daniel will lose some sanity. Even if the Lantern was on, Daniel will put it down by himself.
After clearing the rubble blocking the corridor with explosives, an area above that looks very similar to
he Back Hall comes into view. However, this isn't technically possible because the storage extends away from the Back Hall and there is no hole to be found on the ground of the Back Hall to show the Storage.
There are four Grunts. The first is triggered when Daniel picks up the drill part in "Old Tools" (see map to the left), the second is hiding in the room marked "Grain", the third when he picks up either of the two Machine Room rods in the final storage room, and the fourth shortly after he walks over the rubble he cleared with the explosive on his way out of Storage.
Upon returning to the food storage area after collecting two rods, the door to the "Grain" room will be open as if the Servant Grunt who had been there earlier had left.
Tinderboxes can be found all over the place. Oil can be found in the "Meat" locker hidden among several barrels, in one of the rooms in the "Equipment" area, and behind the long table in the "Food Storage" area. Thankfully, the player should have enough oil by now to get through here since this is the first really dark area that requires the lantern since the Refinery.
Upon Daniel's successfully retrieving everything needed from Storage, the Shadow will foul the Back Hall with its fleshy deposits and the Back Hall's fountain with blood.