Head to the plaza on the eastern side of the western-most island in the Loop to meet up with Damien. Damien has played us, again, and this time Aiden's family is paying the price.
Rush over to Nicky's house for another confrontation with your old partner to find out what has happened with Nicky and then triangulate Jackson's location. Hop in the neighbor's car and quickly make your way to the L-train station for a scene.
You need to hack the train so that it leaves the station before the Fixer's board it and find Jackson. You have a few options to deal with the Fixer's, but I suggest you head to the south side of the station, across the street.
You can now set up any traps and hack the cameras when ready to get the training running.
Aggressive Route - Stop Them at the Station
If you have IED's crafted before this part of the section you can quickly toss them at the two cars to take them out. This will halt them in their tracks and you will only need to mop up the remaining enemies to advance the mission.
Cunning Route - Block the Path
The first intersection that the two cars pass has a set of Blockers that you can hack if you have the ability. This will stop at least one car, which you can ignore, and then you need to follow the second. Ram the second, or use Traffic Lights, to cause them to crash and burn and then mop up the remaining enemies.
Aggressive Route - Spin Outs
If you miss the opportunities to hack the Blockers or Traffic Lights, simply go for ramming. Once you take one car out you can ignore the occupants and continue after the second car, as you are not required to kill the Fixers until the objective updates. Watch out for more hacking opportunities as you chase the cars down and you should be able to get them before they reach the next station.
After the Fixers are taken care of you can head to the next station and meet up with Jackson.