Second Chance is unlocked if DeFalco escapes with Chloe Lynch in the mission, Karma. The goal of the mission, although it isn't specified as her, is to rescue Chloe. The only problem is that the target can be in one of a number of buildings, which is completely random and changes upon each playthrough of the mission.
You need to go from building to building, clear out the enemy troops and Quadrotors, then search inside to see if the HVI is inside or not. Once you find her, cut her loose and you will be able to even switch to her for the rest of the mission (she's armed with a handgun). With her now free, all you have to do is get to the VTOL to escape.
