You are in charge of the ground team dropped into Eden Prime, an Alliance colony under attack. Your primary goal is to find and secure the Prothean Beacon.
This mission is acquired immediately upon completion of Prologue: On the Normandy.
The scene opens with the SSV Normandy flying above Eden Prime and Joker giving a status report. Nihlus announces his intention to move up ahead and Anderson gives Shepard, who's squad is Kaidan and Jenkins, his mission. Upon landing you must move through the clearing and up to your left. Kaidan and Jenkins comment on the gasbags up ahead. As you move through the path to your left, you find bodies which Jenkins comments on. You enter a second clearing, which sparks a cutscene.
Shepard orders Jenkins to move up ahead which ends with three Geth Recon Drones killing him. Take out these drones and examine Jenkins' body. You can tell Kaidan to get his act together (renegade) or reassure him (paragon). After the cutscene, move through the clearing and go right. Once up ahead, you encounter more Recon Drones. Destroy them and a cutscene sparks. Gunnery Chief Ashley Williams is shown running, being pursued by two Recon Drones. She manages to pick them off, but is spotted by two Geth Troopers, who have just impaled a colonist on a Dragon's tooth. Now move up and take out both Troopers for a cutscene. Ashley explains how she escaped and that the hostiles are Geth. She will replace Jenkins as a squad member and you must move up to the dig site.
You find another group of Geth Troopers, but dispatching them should be simple. Once eliminated, a cutscene sparks where Ashley comments on the Beacon's absence. You regain control and move up into the Research Camp. A cutscene plays showing impaled colonists, now converted into Husks, getting lowered from the spikes and attacking you. There are only three, but their nova attacks can drain your shields quickly. One eliminated, you can choose to continue or enter the shacks for some loot and to spark a conversation with Dr. Warren and Manuel. If you move up a cutscene sparks showing Nihlus approaching a turian only to let his guard down and talk to the turian, who is revealed to be named Saren Arterius. Quickly lying to him, Saren draws a pistol and points it to the back of the oblivious Nihlus' head. You regain control and hear a gunshot. As you enter the spaceport, you see a gigantic, megadreadnought flying up into the sky at frightening speed.