Mind the Gap - Call of Duty: Modern Warfare 3
Once in control, move along the alley and take out the first tango who exits the door. Enter that door and kill two sleeping guards inside. Exit to the alley and enter the building just ahead. You'll find the first of the two intels in this part of the mission in the corner of the dark room.
Regroup with your team and continue clearing the next warehouse. Once you reached the top floor, there will be a heavy firefight by the docks. Join in and clear it. Once clear, your team will move behind the truck. Don't open it yet. Head to the docking bay, climb the stairs and follow the walkway until you reach a room with the last intel on the desk.
Go back down and open the truck's door. More enemy forces will appear. Just mow them down and make your way to the construction site. After clearing the area, run to the pickup truck and board it. You'll have unlimited ammo during this sequence so continue firing at the hostiles inside the hijacked train. Keep doing this until the train crashes.
The second part of the mission will now start and there's one intel left to be gathered. Get on your feet and fight your way to the station. Take care not to hurt any civilians along the way.
Go up the first escalator and kill all enemies on sight. The last intel is located behind the magazine counter.
Continue heading upstairs and killing all enemies. You'll finally meet up with the rest of your squad. Continue to street level and move into position. After the truck is stopped, the scene will switch to the Davis family. Just watch the grim scene. Mission complete.