Conflict: Denied Ops

During the midway point in the castle level you'll be inside a cave, after killing of the enemies around the area walk down the slope and across from a sort of small building there's a couple of cells with some FSB agents in, there should be a button to press close by that will open the cells enabling the agents to come out. The agents now follow you and participate in shootouts, though there not the best of shots they can be pretty handy just make sure you kill the enemies first before they have a chance to aim at the agents. 

During the midway point in the castle level you'll be inside a cave, after killing of the enemies around the area walk down the slope and across from a sort of small building there's a couple of cells with some FSB agents in, there should be a button to press close by that will open the cells enabling the agents to come out. The agents now follow you and participate in shootouts, though there not the best of shots they can be pretty handy just make sure you kill the enemies first before they have a chance to aim at the agents.