This is the 12th story progression achievement.
*** Spoiler - click to reveal ***After completing ‘Payback’ return to the Omnistat Tunnels if you’re not already there and head to the marker to start ‘Prisoner X’. Head to Ocean Pier, which can be reached via a building at the far end of Eden Village with the use of your fully upgraded MAGrope. Once in Ocean Pier follow the route to the marker to start chasing down a VTOL. Follow the VTOL until you can latch onto it with your MAG then let it take you to your destination, where you’ll drop to a rooftop.
Follow the marker over the edge of the building to slide down to a lower level, then go through a vent and work your way through the building until you get to a room full of large fans. One of these fans will stop periodically, and when it does you need to jump through it. Once through, make your way down through the server stack to a terminal. Activate the terminal then follow the path to the exit. Before you can escape you’ll have to fight several K-Sec while you wait for a train to take you to safety. Once the train arrives jump onto it to complete your escape. The mission will end shortly after and the achievement will pop when you disembark.