Dishonored

Mission: 7 - The flooded District
missable Achievement: yes

Its a Sidequest, but you have a Missions Marker, should't be a problem to find. You don't need to get you belongings, but i highly recommended that you get your gear, if you don't, you don't have a Crossbow till the end of the Game (two more Missions).

Mission 7 The Flooded District.

Your Gear is being Held in The Greaves Oil Refinery - A completely Separate Location to the main objective.

Easy Method

In the building where you recover make your way to the top of the building, past two assassins and onto the roof. Head along the Waterway to the building just in front, there are some rats & gold coins etc.

From this building head to the opposite side of the waterway. You will see a long chain hanging down (If you have dark vision easy to see). If you dont have Dark Vision and can't find the chain, make a save buy dark vision and when you have located the chain reload your save.

Climb to the top of the chain and enter into the building, through the roof. Collect the loot from the bodies and you will come to a door leading to the Greaves Refinery.

Blink across to a building marked control room. Grab an empty whale oil tank take it outside the building and fill it. Go back into the room and and power up the stair controls.
Make your way up the metal flights of stairs on the side of the building, and follow the path,

Climb up two chains, wait for the assassins to leave and you will be inside the refinery.

You now need to power up another circuit. Head to the right and you will see oil tanks behind some metal bars. The wood above the bars is breakable, so climb onto the crates and melee the planks. Grab an oil tank and throw it through the gap, then blink yourself through. Fill the empty tank and place it into the power slot. Lowering a bridge.

You will see a chain in front of you, the chain will take you directly to your belongings. You will see lots of enemies on the way down. I would recommend taking them out on the way eaither by chocking them out or knifing them depending on your preferred chaos.

As soon as you interact with your belongings the achievement will pop.