During this mission, you will only be able to bring along James and either Ashley or Kaiden, depending on who you allowed to live all the way back in the first game. Bring up the menu before beginning the mission in earnest, as you will have a few points to spend leveling up your party. Upgrade whichever skills are to your liking, and then head down the ramp ahead. A group of Cerberus soldiers will be waiting for you, armed with assault rifles and barriers. Kill the Assault Troopers before focusing your fire on the shielded enemies.

Head forward and proceed into the base. James will leave your party here and Liara will enter it in his place. Conveniently enough, her abilities will be useful in the upcoming battle. Use Singularity to yank the entrenched enemies out of cover and shoot them while they recover. This battle should end quickly. When you are done, head to the lift controls and examine them to move the lift. The car on the lift will create a makeshift bridge to the next area, so climb up the crates and onto the car to proceed.

The next room will be full of unsuspecting enemies. While your instincts may tell you to open fire (and in previous Mass Effect games, this instinct would be right,) don’t forget that you can now get stealth kills on enemies. Take cover as you enter the room and assess the area. Sneak up behind the nearest guards and kill them. You will not get too far stealthily, however, as the enemies will notice your presence soon after the guards begin to fall. When they turn on you, their numbers should be significantly reduced. Plant yourself behind some cover and fire out at them to finish the job. When all is said and done, leave cover and go into the security room. Here you will find several useful items, including the Ariake Technologies Gauntlets, M4-Shuriken, and a med kit. Once you’ve grabbed all of the items, activate the security terminal.

You may now head outside. Collect the Kassa Fabrication Chestplate between two ladders as you exit the area. Proceed into the derelict airlock to find a data pad which you can read to earn a few experience points. Another team of Cerberus soldiers will find you and begin to attack. Head to the sinks and take cover behind them. Wait for the enemies to begin to enter the area. They will begin to open the windows. As your line of sight clears on them, bring up the abilities wheel and throw a Singularity their way using Liara. The area of effect on this attack should be wide enough to catch most, if not all, of the incoming soldiers in its grasp. Hit them hard with your guns afterwards. The rest of the enemies, if there are any left at all, should be easy to defeat. Simply stay behind cover and pick them off with your rifle.

After the battle, head to the right. You will find a small room. Inside of the room are a medi gel and the controls to alter the environment of the station. Activate the controls to open up a path to the next area. Head through the passage that was just opened and run behind the barrier. Here you will find some SMG Ultralight Materials. Collect them and proceed to the corridor ahead. Enemies will begin to file out and impede your progress. Use Singularity again to slow the progress of your enemies. Pick them off with a sniper rifle as they lie floating in the air. Try to hit the Guardians with the Singularity; these shield-toting enemies can become a nuisance if left alive for too long.

When you have dealt with the first group of enemies, head into the connecting corridor to trigger a battle against several more enemies. As the corridor is quite confined, use similar tactics to the last battle to emerge victorious. Head down this hallway and into the next room. This area will be in the process of being sterilized by powerful beams. These will damage you if you touch them, so wait for them to disappear before running into the room. Activate the controls inside of the room, on either side of the area. Grab the Shotgun High Calibur Barrel, examine the data pad, and collect the medi gel inside of this room. When you have found all of the items, turn to the left to find your exit. Proceed through the door and take cover behind the pillars just as Ashley or Kaiden does.

Just as you do, a turret will begin to fire upon your position. The turret is highly damaging, so be sure to let your shields recharge fully if you are hit by this weapon. Instead of facing the turret head on, proceed to the side to enter to control room. A group of Troopers and a Centurion will be waiting for you here. Kill the enemies in the room using Singularity; the small area of the room will increase the effectiveness of the attack. You will find several medi gels, a data pad, and the Sniper Rifle Concentration Module inside of this small room. Grab them, and then flip the switch on the panel to initiate a cutscene. Either Ashley or Kaiden will advise you to flank your enemies. Use your squad commands to group them both up together to increase their odds of survival. Head to the opposite side of the room and let your companions take most of the heat while you enter the tram. Flip the controls and ride the tram to its conclusion. You will be ambushed by a group of enemies here. This will be but a small group, and will be easily dealt with. Kill the soldiers and steal their vehicle to get to the next and final area of Mars.

There will be numerous enemies in this area, so watch out on all sides. The enemies will spam grenades. Keep on the move to avoid them. Keep using Liara’s Biotics as frequently as you can to thin out or stun the enemy hoards. Once the enemies have been downed, grab the Shotgun Shredder Module, the M-15 Vindicator, and a pack of medi gels from the room in the middle of the area. Head through the door ahead to find the Illusive Man and his new partner, Dr. Eva. Groups of soldiers will emerge and begin to attack, but you should ignore them and focus on chasing down Dr. Eva. When you reach the roof, she will charge you. Shoot her to complete the Mars mission.