|Warning: This article is a walkthrough/guide and may contain plot spoilers.|
 "Alert, Borders inbound"
This is the first proper playable level of Halo 2. You will spawn at the top of a set of stairs with Miranda Keyes already at the boxes where you need to go. Proceed down the stairs and grab a Battle Rifle and an SMG from the boxes. Proceed through the unlocked door into your first battle. You will hear Johnson telling you to focus your fire on the door at the back of the room. Use one of the 6 windows in the room as cover before the Covenant break in. Alternatively, you can jump up on one of the holo panels and get over the door to look down on the action. Watching through the window, you can see the Covenant drop ships latching onto the air locks of the Cairo Station, just like they did to get on board the Pillar of Autumn.
 Home field Advantage
Wait until you hear Covenant behind the door. You will see them welding and forcing their way in once you see a burning light coming through the door. Once they've broken through, make sure you have cover. A hail of plasma fire will come out of the explosion at the door. The room and the landing above the door will not be full of Grunts and Elites. This is the first time you will see the new Covenant Weapon, the Brute Plasma Rifle. When you're finished dealing with the first 2 waves of Covenant, go through the door they broke through and head right. There will be more Grunts and Elites down there. Handle them with your Battle Rifle and head up the stairs to the right of them. This will lead you into a semi-open room with a turret mounted to your left. Jump on the turret and give covering fire to any human forces in the open area below. Continue on through the room and down the stairs outside the door, to the left. There will be more Grunts and Elites taking cover behind human barriers down here. Use your Battle Rifle to take them down with some precision shooting.
When you head left, you will come out in the room that you just shot into when you were on the mounted turret. There will be more Covenant on the small raised platforms in the room. Once you take them out, you will get a checkpoint and feel the rumble of more pods latching onto the Cairo. Head out the back of the room, to another set of stairs that will bring you back up to the first floor and through a door way into a shuttle bay. When you enter, there will be marines using the mounted turrets to hold off the covenant forces. Help them out any way you can. There will be more ammo for your weapons lying around on fallen soldiers and in ammo piles strewn around the shuttle bay. Ressuply accordingly and continue fighting in the Shuttle Bay until you've cleared all the Covenant. Be sure to watch the Covenant Pods that are latched onto the Shuttle bay doors. Covenant stream out of these pods, so it's easy to use them as a bottle neck to take out the Grunts and do some damage to the Elites before they hit the ground.
After you've defeated the forces in the room, your focus will be shifted to the Malta, which is the sister ship of the Cairo. The Covenant seem to be retreating, but looks can be decieving, as the Malta explodes as the Covenant leave. After another wave of Covenant in the Shuttle bay, your focus will now be shifted to the Athens, another ship in the fleet, and it will too explode.
Cortana's assessment is that the Covenant have brought a bomb on board all 3 of the ships, and now the Master Chief has to find and dispose of the one that's been brought to the Cairo Station.
 Priority Shift
There are 2 doors in the floor of the Shuttle Bay, they will now unlock. Head down into the room below and watch for the Grunt and Elite team down there. Once you've killed them, an Elite with Active Camouflage will enter through the door at the other end of the room. Kill him and proceed up into the armoury again. When you go into the Armoury you will see the armourer getting killed by a pair of Elites. Grab his Shotgun and deal with the pair of them, then leave and enter another room like the one that you shot down into on the mounted turret at the beginning of the mission. This time though, there will be Covenant on the landing and Grunts manning turrets. Make sure to take them out first because these turrets are lethal at close range. Go through the back of the room and up the stairs into where the Grunt was on the turret on the landing and continue out the back of the room, down the back set of stairs. You will meet Sergant Johnson and Miranda Keyes in a battle with some Covenant. Help them dispatch the enemies then follow them. You will come across an airlock that only the Master Chief can exit, because of his suit.
 Authorized Personnel Only
There are two things to notice in this area. This is the only time in the game you will experience 2 things. One, it is the only time you will see Elites with Jetpacks in Halo 2, and two, it's the only time you will be able to play with reduced gravity atmosphere. The Master Chief can jump much higher and clear larger gaps in reduced gravity. It's surprising that Bungie didn't take advantage of this and put some hidden Easter Egg in a dark corner somewhere.
Anyway, when you're finished dancing around in reduced gravity, head towards the siren spinning on the wall. This is the entrance to the next air lock and where you need to go.
When you come into the arilock, you will find a large room, full of Drones. Take them out promptly as there is a large lift on the way up that has a lot of enemies on it. Once the lift comes up, you need to clear the lift then use it to go down. As you're going down, you will see 2 Covenant Carriers coming for the Cairo, Cortana is instructed to fire on the first carrier. You now have to leave the Cairo again to get to the next section. You will find more Elites with Jetpacks who are dual wielding Plasma Rifles. Take them out and continue across the hull of the Cairo. When you go back inside, you will find a lift that leads down to where the Elites are protecting the bomb before it goes off. There are quite a few of them, so prepare for a battle.
 Return to Sender
The elevator will dock on the bottom level and when the door opens, you will have the element of surprise. Use your Shotgun at first and sneak up on at least one of the Elites. Use Plasma Grenades to get the jump on the group of Elites around the bomb. With a bit of crafty avoiding, you can take them all out with no real problems. One you take them out you will hear a communication from In Amber Clad's captain, Miranda Keyes. Then and epic cutscene takes place that sees Master Chief using the air lock to launch the bomb back at the Covenant Cruiser.
After that, it's on to the next level, Outskirts.
Related ThreadsHalo 2 Movie: Cairo Station - last post by @ Jul 26, 2005
This WILL help on Cairo Station on legendary! - last post by @ Dec 3, 2004
On top of Cairo Station - last post by @ Feb 6, 2005
Cairo Station - last post by @ Dec 21, 2004