Long Road Ahead

Long Road Ahead is a quest that can be obtained in the Commonwealth in Fallout 4.

Synopsis
The Sole Survivor decided to hire a mercenary in Goodneighbor, however he comes with a little more baggage than expected. Once the Sole Survivor gains the trust of MacCready he will ask his employer to travel to the Massachusetts turnpike interchange to kill his former associates, Winlock & Barnes. Once this Gunners way point is laid to waste he will thank his employer for their trouble and continue to follow.

Once he trusts you enough he will confide in the Sole Survivor that the reason that he is in the Commonwealth; to find a cure for his son Duncan. His only lead is a rumored cure in the Med-Tek Research building. After wading through ferals and automated security, the pair obtain the cure; Prevent. Once obtained the cure must be transported via Daisy's caravan connections back to MacCready's family in the Capital Wasteland.

Walkthrough

 * 1) Increase MacCready's loyalty enough by doing things he likes, then talk to him. He will ask to travel to the Mass Pike Interchange and deal with Winlock and Barnes.
 * 2) Travel there and enter the upper levels of the interchange using either the north or south gantry elevators. Then simply find and kill both. This will remove them as a threat to MacCready and convince the Gunners to back off.
 * 3) Continue traveling with MacCready.
 * 4) Next, MacCready will confide that he needs to find a cure for his son's illness. He will want to travel to Med-Tek Research. Head there.
 * 5) The cure can be obtained by clearing the location. First, find  the executive terminal to unlock the containment. It's located on the highest level of the first part of the building, accessible through the rear stairwell and then the collapsed floor. MacCready will hand over the password for the executive terminal after entering the room.
 * 6) After turning off the containment on the terminal, the secure part of the facility will become accessible. Open the airlock, then enter the secure section and use the security terminal to open the security doors. The cure is located in the lower levels. The elevator connecting to them is in the back of the secure section.
 * 7) The cure is in the laboratory at the end of the level. Simply navigating through the maze-like corridors will lead to it. Open it with the terminal on the wall and collect the cure from the table in the center.
 * 8) Talk to MacCready with the cure in inventory, then head to Goodneighbor to hand over the cure to Daisy and complete the quest.

Bugs

 * When the player shows up to Med-Tek with MacCready, the game will occasionally not trigger the script when the player reaches the 3rd floor executive terminal and the quest will not update to recognize that. Reloading usually works.