This achievement is unlocked when you successfully pick the lock of your cell after being sent to jail. When you are caught committing a crime--theft, assault, pickpocket, etc.--you have three options. You can resist, pay a fine, or go to jail. You must choose to go to jail. Once there, you find your equipment has been removed but you have one lock pick remaining. You can make a save before trying to pick the lock & can revert back to it if the lockpick breaks. The achievement unlocks after successfully picking the lock.
When you choose to go to jail, you initiate a side quest, "Behind Bars." The achievement does not require that you complete the quest--it pops right after picking the lock. To complete the side quest you must escape the jail either by stealth or combat. If you escape by combat, you commit other crimes--jailbreak and assault. This temporarily turns the inhabitants of the town in which you were jailed against you. Nevertheless, if you leave & come back after a while, the town returns to normal all grudges forgotten. If you escape by stealth, you will get a "Crimes Cleared" notification along with the quest completion and can resume your business in the town.
The achievement can be done in any town. The first town you come to is Gorhart and this is the earliest opportunity to earn the achievement. Commit a crime--pickpocket a citizen, steal from an establishment, or assault someone, etc. When apprehended, choose to go to jail. Make a save before you try to pick a lock. The Gorhart jail is classified as an 'easy' lock, but the one pick you have is very brittle so expect failures in a trial & effort ordeal. I start with middle of the left side. If the lock breaks immediately, I go to the middle of the right side. If it breaks immediately again, I try middle of the bottom. If the pick vibrates, you are close so adjust in one direction or another. The mechanism shown on the game screen looks complex, but the solution is simple--guess the position of the lock pick with
and move the slide left to right with
. If you fail, reload the save and try putting the pick in a different position. If you barely nudge the slide with
, you are less likely to break the pick & can back it to the left. Move the pick to a different position and try again.
The video below shows this process starting with the crime--an assault against a guard. To strike a friendly person, unequip your primary weapon and then press
to go into aggressive mode. Otherwise, you cannot attack friendly characters. Crouching, by pressing
, also puts you in an antagonistic mode. Get near the person to be assaulted and press
to punch. It may take more than one strike to connect. You will be apprehended and can choose to go to jail:
Because you are level 1 when you enter Gorhart, you can also earn the below achievement for killing an enemy four levels above you by killing a prisoner or a guard. If you kill a prisoner with the stealth assassination taught in the prologue, you can sneak out the jail behind the guards & clear your crimes: