The ability to pick locks, open doors and safes. More importantly however, it's also used to break OUT of situations: cages, jails, handcuffs. It's for those who value freedom and don't wait around to be rescued.

– In-game description

A door/container is indicated as being locked when the cursor changes to a padlock symbol when moused over. Lock picking can be initiated by holding down the ALT key and right clicking, or hold right click and selecting the "Lockpick" option. Your selected character will then move to and attempt to pick the lock. Progress is represented by a bar that fills in from left to right where, at the end of each cycle, your character has a % chance of succeeding. This is represented by the percentage in the lock picking progress bar.

It is possible for a lock to be too far out of your character's skill range. Your character will state that their skill is not high enough. A character needs to have at least 5% chance to attempt lockpicking.

Locksmith Training Boxes can be used to improve the skill without putting yourself into dangerous situations. This is useful during the early game when success chances are extremely low therefore disallowing you from even attempting and preventing you from improving the skill. Aside from building these training tools yourself, they can be accessed in Shinobi Thieves' towers if you are allied to them.

Similarly to other training equipment, a character may train only to a certain level, beyond which your character will still "train" but no progress will be made to the next level.