Tip before we start (Save your game before you do anything)
Alright, first thing is first go to WhiteRun and find a guard hit him and then hold X to sheath your weapon. Once you sheath your weapon a dialogue will come up and the option you want to choose is submit to jail or something along those lines
Now that you are in jail and have loaded in find a trapdoor on the floor near a body, it will have a novice lock on it but is far from hard and should not give you much issue. Once the trap door is open jump down and work your way through the tunnels until you come to a door, the door will be expert but take the stairs to the right of it and circle around and go through the tunnel above it and you can drop down behind it. Keep working your way through and you will find a wood ladder which will allow to enter into a guards barracks. Once you enter the achievement should pop but if it does not exit the building
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