This is the other mission Jake told you about. Drive to the destination carefully, not like a maniac, although it is fun. Here are the directions to get to the next destination:

Turn right because left is blocked by the Triads

Take a left out of Chinatown

Take a left then a right immediately after(almost like an S-turn)

When the road divides, take the far left path

Keep going over the pavement

Turn right at the next turn after the pavement

Turn left at the intersection and stay right

This time, stay right BOTH times when the road divides

After the road meets again, go through the next set of lights

Turn left at the next intersection

Take the second right which is at a decent-sized intersection

Drive over a few pavements

Turn left when you have to choose

Turn right at the next roundabout

Keep going till the next roundabout

Turn right then right again

Take the next left, then right, then left

Turn left and get out at "Durant and Taylor" which is on your right. (A blue car is sticking out of the opening)

The first thing you should do is run up to the entrance and take the guard hostage, and break his neck. Take his AK and run into the area. Find your way to the bottom right corner of the area, which I think is the best place to go. So when you come in the area, go to the right, by the dumpster and let the Yardies and Traids kill each other for awhile, then auto-aim at anyone near you and kill them. Next thing, free-aim with your AK and kill the guards in the right and left window. Wait for some more guards to come up to you and kill them. Then kill anyone in front of you in the middle of this whole area.

Once it seems quiet and you've killed everyone, head forward and to the left to find a small room with a guard with a Shotgun in it and kill him. Once this is done, exit the whole area and make sure to pick up one of the many AKs laying around (There's plenty more where that came from). Outside of the area a cutscene will play with Mark on his phone. He has another mission to do now.