After the cutscene of the previous Mission where Master Chief and Locke had the fight to bring Chief back home, but Blue team and Chief managed to escape from the earthquake and the Fireteam. Osiris is separated from Blue team and must race to catch up. Let’s continue to move on to the Meridian Station and continue with the Mission 6: Evacuation.
Once you start with the mission you’ll be outside the Meridian Station and need a Warthog to head straight towards the orbit to get the Space Elevator. The Guardian is being Triggered by Cortana on purpose so you need to get the hell out of there. Do not bother taking the Enemies just drive towards the Space Elevator.
Once you reach near the Elevator you need to Secure the outpost so that Governor Sloan will open the exit door. So start Eliminating those Prometheans and the last way you need to deal with are a couple of Knights so get your ammo refilled. Once you activate the Elevator, Slone will let you know how Cortana has planned for a better future and he is going to help her for her cause.
Keep moving on the other side and take the Elevator, once it crashes down you’ll have some Prometheans getting ready to fight so just keep eliminating them. You and the Fireteam must be prepared as there will be 3 waves of Prometheans to handle. After the Elevator crashes head up and moves towards the Emergency Exit to continue.
Keep climbing up and eliminating the enemies soldiers. Make sure you keep your Fireteam up to date as you climb up. There will be continuous waves from the enemies so just focus and keep jumping and climbing up.
As you reach the top floor, take a right and find the Pelican to escape from the Area. Use the D-pad to locate it and once you are into the Pelican, get the hell out of here and the cutscene will start, end of Mission 6: Evacuation.