Niko can find Derrick in the same park he found him for the mission Smackdown. He will tell Niko that Aiden O'Malley, an old friend of his, has been collaborating with the LCPD, giving them information about his former criminal associates. Aiden believes Derrick snitched on him, and so Derrick is afraid that Aiden will snitch on him now. He asks Niko to kill Aiden when he is being taken back to the Alderney State Correctional Facility.
The mission starts with Niko ready to do as he is told, when Patrick "Packie" McReary calls and informs him that he will help him on this mission. He also informs Niko that carrying out the mission as Derrick ordered is a bad idea because O'Malley is under heavy police custody, and if he is killed in the presence of the LCPD, Derrick would be the first person to be questioned about it. To avoid this, Packie suggests making it look like Aiden is being broken out of jail.
Packie further tells Niko that he left a Biff truck in an alleyway that will be useful in the jail bust. He hid a Rocket Launcher inside as well. The first part of the mission is to pick up the truck which is now marked on the radar. Once inside, Niko calls Packie, who is out driving a truck of his own and following the convoy that carries Aiden. He tells Niko that the plan is to ambush the convoy in the Booth Tunnel
The truck provided by Packie must be driven to the Booth Tunnel and, once inside, parked perpendicular to the road so that it serves as a roadblock. The game goes to a cutscene. The convoy carrying Aiden O'Malley arrives and is halted by the truck. Packie arrives in his vehicle, and does the same as Niko, sandwiching the convoy between the two trucks. The police are more than suspicious by this point. One particular officer exits his squad car with the intent of instructing Niko to move his vehicle.
The cutscene ends with Niko outside the truck on the opposite side of the convoy, now armed with a rocket launcher. Now the fireworks begin. All of the police and NOOSE officers must be eliminated before proceeding. However, the Stockade in which Aiden is held must not be destroyed or else the mission will be failed. Packie will help eliminate some officers. The two police cars nearest Niko can be safely destroyed with the rocket launcher, after which gunning down the few remaining officers with your choice of assault rifle shouldn't present much difficulty.
Once the officers are down, Niko will hop in the driver's seat of the van, and Packie will sit in the back and keep watch on Aiden. After leaving the Booth Tunnel, the player must get rid of his wanted level. This can be done either in Alderney or Algonquin.
After you have lost your wanted level, Niko relays to Packie that the van stands out, and they have to ditch it. A new destination will be marked by the GPS, where the Stockade must be parked and changed for another, less conspicious car.
Once all three men are inside, Niko will be instructed by Packie to drive to the cliffs in Leftwood. The destination will be marked by the GPS. On the way, Aiden will ask about who sent Niko and Packie to help him escape and where will he be taken. Packie will give answers hinting at Aiden's execution.
Once you get to the cliffs, all three men exit the car and the game goes to a cutscene. Watch Aiden preach his gratitude on the edge of a very disappointingly low cliff. Aiden requests once more who put Niko and Packie up to springing him free, and to his dismay, "Derrick McReary" is the answer. Packie angrily condemns Aiden for his loose tongue and orders Niko to get rid of him. Packie gets into the car, and drives away leaving Niko with Aiden.
The player may kill Aiden in any way he likes. If he is shot, a small cutscene will show him falling off the edge and hitting the rocks, ending up in the water. Once Aiden is dead, the mission is over and Niko will call Derrick to tell him of Aiden's death.