This mission is unlike the others and becomes active after mission 7 but cannot be completed till you have finished mission 11.

Objective 1: Take the First Letter of Dee The mission starts after you hand the Contagione to Dr. Knight and in return he will hand you the first Letter.

Objective 2: Use CCTV Monitors to find the Letter Bearers Return to your safe house and examine the CCTV monitors and the locations of the letters will be revealed if you have been hacking all the Junction Boxes you have come across along the way.

Objective 3: Collect Dee's Letter in Victoria Memorial At the end of the mission Raid the Military Armory you can find the next Dee's Letter inside the sewers and use the keycard you got from Colonel Waverly to open a cell door which leads to the armory. There will be a passage not far from the door leading to the shortcut to the safehouse. Take the passage and it will be on a woman's corpse in a corner of the room.



Objective 4: Collect Dee's Letter in Brick Lane Flats

This can only be obtained after you gain the Prepper Pad upgrade that scans the mysterious symbols. At Brick Lane Flats find the warehouse buildings you were in earlier in the game. Go back to the office on the top of the warehouse and back into the room with the keypad locked door. Look around for a symbol on the wall. When you find it you need to stand in a particular spot in order for this to work. Stand where you can see a window between the two offices. Look around and line up images scattered around till they form a raven. When you get the raven image revealed scan the image and it reveals a code. Go back to the keypad locked door and enter the code. Inside is a body with the letter.



Objective 5: Collect Dee's Letter in Brick Lane Markets

Head to the Brick Lane Markets and go to Hanbury Greens. When you arrive there go through the chain-link gate which leads to an alleyway. Go down the path until you reach some stairs. Go past them and you'll soon find a pile of trash. When you find it use the C4 to remove the trash and reveal the path leading to the Letter.



Objective 6: Collect Dee's Letter in Spitalfields Green

Go to Spitalfields Green and go to Quaker Park. When you get their go past the iron barricade located next to a barred gate you previously couldn't enter. Take out the Prepper Pad and hack the door which leads to a brick wall with a hole on it. Go through the hole and you find a body holding the letter.



Objective 7: Collect Dee's Letter in Tower of London

Go to the Tower of London and head to the Green Park. Go back to the second pier you were at earlier. It is the one with the drawbridge. Take out the Prepper Pad and hack the locked door nearby and head down the newly opened path to a tugboat. On the boat is a body holding the next letter.



Objective 8: Collect Dee's Letter in Baconfields

Go back to Baconfields and head back to the wasteland. Look around till you see a shed. To know you've found the right building the shed is located near a pond. When you find it take out the Prepper Pad and hack the lock and enter the shed. In the shed is a body holding the letter.



Objective 9: Bring Dee's Letters to Dr. Knight.

When you collect all the letters return to Dr. Knight and hand them to him. The best time to give the letters back to him is after ending the mission Refuel the Generator Part 2.

Dee’s Letter #1 – In the Palace Underground, the doctor will give you this through the box when he gives you the mission.

Dee’s Letter #2 – Victoria Memorial, fast travel to the sewer and follow the Prepper mission to get Colonel Waverley’s keycard, open the sewer door with this keycard and loot the letter form a dead body.

Dee’s Letter #3 – Brick Lane Flats, in the Old Brick Warehouses, After completing the Tower of London mission, and getting the black light and Cypher pad upgrades, find the offices on the upper floor and you’ll find a keypad. Go into the other room, where the full painting of the raven is on the wall. Look through the window, toward the keypad and line up the partial painting of the raven, with the black paint on the window and you’ll be able to scan the code. It was 3391, I’m not sure if they codes are random or not.

Dee’s Letter #4 – Brick Lane Markets, in the area called Hanbury Green, find the building with the outdoor staircase leading up to an open flat. Under the staircase will be a pile of trash you can set some C4 on, loot this letter form a body after blowing up the trash and going through.

Dee’s Letter #5 – Spitalfields Green, in the Quaker Park area behind an iron barricade. You’ll have to play through the story until you get the Scan Hacker upgrade for the Pad to get this letter.

Dee’s Letter #6 – Tower of London, in the Tower Pier area, you’ll have to wait until you come back to the Tower of London with the Scan Hacker upgrade and this letter will be on the deck of a tugboat that is docked at the second pier.

Dee’s Letter #7 – Baconfields, in the Darwin Yard area you’ll find this letter in a shed near the pond and excavator machine. As with letters 5 and 6, you can’t get this one until you have the Scan Hacker pad upgrade.