In last two missions, you were playing as a SAS soldier, now it's time to become an American Marine. After landing (#33), follow lieutenant Vasquez. You will get to a building (#34), where, the leader of the terrorists, Al-Asad is supposedly staying.
After the door is blown up, get inside and down the stairs (#35). Then kill all the terrorists but mind the enemies hiding behind the boxes. Before you keep going, take another weapon, for example Kalashnikov (you can find it on the tables in the main room #36). There's a high probability, that you will run out of ammo if you don't change your weapon.
Use the stairs to get outside (#37). You have to get to a Tv station, and that won't be easy - you will have to get through the city, controlled by terrorists (#38). Follow your team, and you will get in the middle of a combat. Eliminate the enemies and watch out for the reinforcements that will keep coming.
There are two ways leading to the Tv station. No matter which one you choose to follow, you will get to a crossroads. A car with a terrorist operating a machine gun will show up there (#39). Kill him and keep going (#40).
There you will encounter more terrorists. This time they'll come in greater numbers so you will have to be extra careful in order not to be killed. Make use of the frag grenades, that will help you to deal with larger groups. Try to stick close to your team -your teammates aren't as efficient in killing as you but they can be helpful for instance by throwing away the enemy's grenade.
After the continuous struggle, you will get to the Tv station (#41). When the door is blown up, get inside.
Go straight, killing the enemies (#42). You will get to a big room (#43), full of terrorists. To take over this room it's good to get to the other side of it, by sticking to the left wall. Hide behind the cubicles and eliminate the enemies, mind the terrorists on a balcony too. It's good to use grenades here - they can make your enemy confused and that is why it'll be easier for you.
After dealing with the enemies in the main room, clear the little ones next to it. Then your commander will give an order to advance to the second floor. Get to the door and wait for Vasquez to open it. In a hall (#44) you will meet the other Marine squad. Go up the stairs and head straight. From the roof (#45) you can shoot at terrorist that are on the parking lot, but it's not necessary.
Go straight ahead. You will get to a studio where Al-Asad was supposed to be. Unfortunately there won't be anyone inside.. (#46)