During the level PAVEL, you will come to a section where you enter an airlock and are told about your watch's functionalty. After exiting the airlock, you come to a small hallway with some enemies. Take out the enemies, and at the end of the hallway, on the right hand side platform, you will see a small command desk with a switch/lever on the left side. Walk up to it, and interact with it in order to free the prisoners, and unlock the achievement.