Angels of Death

Chapter 2, floor B3. Clear the gas room section. Unmissable.

Solution: Walk to the black cabinet by the safe, take Scissors.
Use Scissors on the mattress. Get Small Key.
Use the key on the small safe. Get Wire.
Look at the dead body.
Trade places with Zack.
Get Poker from shelf next to small safe.
Get Bag of Weights from the shelf next to that one.
Move the corpse and take the Severed Leg.
Break open locker on the right. (Warped locker) (Mash A to break) Get Brush.
Swap to Rachel
Use Brush to clean the wall on the far left.
Use the Severed Leg on the scale.
Weight will be used automatically.
Interact with the red and gold box.
Get Battery-Powered Lantern
‘Consult’ Zack.
Use the Remote when you interact with the grate.
Go forward until the two way, go left. Poker will be used.
Turn the poker left, down, right, down, right, down.
Get Card Key.
Walk to the black box with a green line by the door.
Dialogue Scene.
Save.
Use Battery-Powered Lantern
Use Wire
Use Rag
Get in the Big Safe by the gas mask.
Cutscene.
Exit the room.
Dialogue scene.
Achievement unlocked.