After Rico Valasquez Joins his team, Captain Templar proceeds to the Vektan Slums. He first has to fight his way down a building that has several floors, each with a squad of Helghast defending. After exiting the building, they arrive in the dirty slums. They reach the mall where Hakha was said to be hiding. They find a large group of dead ISA soldiers, along with the information that Hakha has been escorted out of the mall by helghast soldiers.
After fighting through the slums, they finally reach Hakha. They learn the stunning information that Hakha is a Helghast. After seeing that, Rico was about to kill Hakha until Templar stopped him. In the confusion, Hakha takes Templar's M82-G Assault Rifle, and shoots a Helghast soldier that had snuck up on them. He then kindly gave Captain Templar's assault rifle back. After this action, the squad had figured out that Hakha was an ISA operative after being lead by the fact that Hakha looked like a Helghast.
[Section 1-"Stairs and elevators"]
When you start, Rico or Templar will tell you that the elevators weren't working even before the attacks, so you're forced to take the stairs. There's a Helghast pistol on the floor next to one of the elevators, when you go down you'll expect Helghast soldiers coming at a big group of about 6 to 9, the same happens 2 floors down. Once at the bottom, another group of Helghast soldiers, including an elite will try and hold the exit to prevent you success. After they are dead, go to the corridor in the back and you're done in this section.
Rico- Since he's more of a slayer type and doesn't have the ability to climb ladders, unlike Templar and Luger, he has to take the stairs and kill Helghast soldiers on his way down.
Templar-Unlike Rico, but like Luger, he has to take a side door which will lead to the elevator's maintenance area and has to climb down the ladders, but be careful as some Helghast soldiers will pry open some elevator doors to check if you're going down. Once on the bottom, the Helghast will pry open an elevator door that you can pass and make you meet some Helghast on the bottom of this section. There is some ammo for Templar's weapon next to a dead ISA on the bottom of one of the elevator floors.
Luger-Same as Templar, except one floor above Templar's exit, there will be a airduct for you to crawl out of the area.
[Section 2-"The Slums"]
After you exit the corridor, you'll see a Helghast soldier, followed up by a small group coming up the stairs and some down the balcony. After you go down the stairs, a Helghast handling a MG will try to kill you and stop you from continuing you mission. Kill him and them go left of the MG, the at the next corner, another group of soldiers will appear, after that, go inside and up the stairs, you'll see a electrical cable, take a note of it. Then once you go through the door, there will be a corridor with some Helghast along with some ammo for both Rico and Templar's main weapon. The keep going and you'll find a Helghast down the stairs along with 2 more on the left. After you go around the fence and go through the main path, a dropship will dropoff about 8 Helghast Soldiers, since the dropship can shoot you, it is advised in harder difficulties to let it drop the troops and attack only when it's gone. After you kill them, another small group will appear on the balcony in front. Kill them, go up the stairs and go to the balcony to get around the fence. Midway on that path, there's about 3 Helghast soldiers on the 1st corner. After that, you'll find an entrance to the Mall to the 3rd Section.
Luger: The best about her is that, since she's trained as a Assassin/Sniper, most Helghast will be back turned to you, perfect to stab a knife on their throat and some Helghasts won't even show up. Remember the electrical cable I mentioned? Well, the regular door will be closed to her, so you'll have to take the cable up, you'll find some ammo and a airshaft that will take you above the corridor filled with Helghast that Templar/Rico has to pass. Once on the otherside, there's a Helghast with a sniper, kill him and take the sniper. The same dropship mentioned before will appear, except that you're on higher ground. Since the dropship will shoot you, it's still advised to wait for it to go away before killing the Helghasts below. After you're done on the Higher ground, there's a cable that will take you back to the regular path safely.
[Section 3-"The Mall"]
Next to the dead ISA soldiers is some ammo for Templar's Main weapon and up the stairs to the right is Rico's ammo for his chaingun. Go left and 2 ISA soldiers are trying to kill the Helghast upstairs just to get killed. This is a hard part because you'll have to focus you gunfire on Helghast both upstairs and on the groundfloor, all to get to the end of the corridor. When on the end of the corridor, turn right and more Helghast will come, after you pass around the fire and barricades, you'll have to go up the stairs to face a Helghast handling a MG, kill him and the rest until the end of the 2nd corridor, and then go up. You now have to kill the Helghast on the 2nd floor on the same corridor. After you hit the end of this floor's corridor, go through a door on a glass wall and you're out of the mall.
Luger: Before going up the stairs on the 2nd corridor, there's a door on the right that leads you to a cable. Climb it and you can take out the Helghast handling the MG for Templar and Rico to pass.
Once you start, you'll end up on a metal bridge and you can see some Helghast fighting some ISA soldiers, including one with the rocket that takes down a container and kills 2 of the Helghasts. You can either help them or leave them, not much reward in either choices except a dialog. Once you finish crossing the bridge, go down and you'll end up in a balcony with a Helghast. Look at your right and you should see some enemies on another metal bridge above, then you'll have to cross the bridge, then another to go around some debris and end up with some Helghasts coming down of a balcony. Once up the balcony and in the corridor, there's another group of ISA soldiers fighting a group of Helghasts, both groups separated by a bridge. Once you kill them, you'll cross the bridge where the Helghast were fighting and more will come around the corner, past the corner is a elite handling a MG, so take him out carefully. Then cross the bridge, kill the Helghast around the corner and then the 2 on the balcony. Then cross another bridge and go inside one of those little houses until you meet some Helghast trying to kill an ISA soldier on the balcony, be careful because one of them has a grenade launcher. Once up the Balcony, you'll meet another Helghast vs ISA section. Except there's another elite with another Grenade Launcher, there's a shotgun and some ammo inside one of the little houses. Go through the bridge and there will be more Helghast across the final bridge, kill them and go inside the room to free Hakha.
Templar: Has to take care of the elite with the MG without help.
Rico: Has to take care of the MG with the assistance of Templar.
Luger: Has to climb a cable to kill the elite on the MG from above.
-In the Mall section, there's a hole on the right in the 2nd floor that you can cross it if you sprint over it, avoiding having to go through the escalator up to fight the Helghast above.
-In the Rescue section, then you pass the first Helghast vs ISA fight and go down the stairs to the 2nd section of the slums, you can hear ISA death screams, this might have been another attempt to clear the ISA soldiers from the game to prevent the game from getting slow.