Derrick wants you to kill an old drinking buddy of his called Aiden O'Malley.
Soon after the cutscene, Packie will call you and tell you that Aiden is in government custody, and that there'll be more police protection than the mayor receives. He left a truck for you in an alley way in Applewhite in Alderney City. The convoy needs to go through the Booth tunnel, so Packie wants you to get there first and block the entrance with your truck. Once they're inside, he's going to block the other side of the tunnel with his truck.
To The Tunnel...
Make your way across town till you get to the truck, then climb in. Once you do, a cutscene will kick in where Niko calls Packie. Packie tells you that you're not going to kill Aiden because the first place the cops would check is with Derrick, so you need to make it look like a prison break. After the cutscene, make your way to the Booth tunnel.
Eliminate The Cops
Once you get half way through it, park your truck over both of the markers and watch the cutscene. The convoy will arrive, and you'll need to take out all of the cops. Use the cover from the truck, and also from the wall to the side, and pick off all of the police officers. I suggest using a sub-machine gun, or a full assault rifle for this bit. You can do it without losing much health at all by staying behind the truck.
Lose The Cops
Once they're all dead, Packie will tell you to drive the truck, so get into it. Head down the tunnel, avoiding the cops, then just after you get outside, you should be able to lose them. Niko suggests ditching the truck because you stand out too much. Make your way to the quiet place to ditch the truck.
To The Cliffs
You'll all get into a car parked nearby, then Packie will tell you to take Aiden to some cliffs in Leftwood. Make your way to the destination and park in the mission objective marker.
After the short chat, Packie will ask you to kill Aiden. Regardless if you feel sorry for him or not, there's no choice here. Pop him in the head and watch him fall off the cliff.
- Stay in cover when killing the convoy cops. You won't take much damage if you keep leaning out and getting headshots.
- Everything after the tunnel is simple, just make sure you don't crash the car too much.
- Don't try to walk away from Aiden. You can't let him live and he'll just run away, causing you to miss the cool scene where his body rolls down the cliff into the sea.