Commander Shepard travels to the colony Zhu’s Hope on the planet Feros which is under attack from the Geth. The colonists seem to be barely hanging on and Shepard does what he can for them in the form of helping take out the Geth command post and communications. He also learns of the Exo-Geni headquarters that can be reached using the Prothean skyway. On the way there
the player finds a small group of colonists hiding in a underground bunker of sorts, they claim that they have been separated from the rest of the colonists. Julianna Baynham is one of the few present there alongside a representative from Exo-Geni named Ethan Jeong who is extremely jumpy. Julianna asks you to look for her daughter Lizbeth who she thinks is still stuck at the headquarters, Jeong repeatedly warns you not to go about snooping in Exo-Geni matters and to make the excursion as short as possible. After fighting their way though the skyway the team reaches the headquarters and locates Lizbeth who is alive and well. Shepard ventures into the complex to find answers and runs across a Krogan who is demanding information from an VI. After dispatching of the Krogan, Shepard learns about the Thorian that is buried under the colony, Zhu’s hope. Shepard proceeds to disable the force fields and damage the Geth ship that is attached to the headquarters. He proceeds back to the group in the bunker and confronts Jeong on the issue of the Thorian. Meanwhile, Jeong has reestablished contact with Exo-geni and has orders to purge the place. The player can either talk him down if his charm skills are high enough or threaten him. Alternatively the player can shoot Jeong in the head and kill him instantly. The player also learns that the Thorian is controlling the colonists and that using a simple anti-Thorian gas will temporarily paralyze them and allow Shepard to continue unhindered. It is the players choice whether he/she accept it or not but regardless Shepard battles his way to the freighter that is near the heart of the city. There he encounters the Colony leader as he is struggling with the Thorian for control of his mind; it seems that the Thorian has ordered him to kill Shepard for his transgression but he ends up shooting himself in the head saying that he is free now. The player goes on to move the freighter and descends down a stairway.
There he spots an massive plant like creature that spans many levels, after approaching it the Thorian "secrets" an Asari who claims to speak to him. The Asari/Thorian tells him briefly of Saren and how he betrayed him, he also refuses to talk to the Player and the Asari along with multiple Thorian Creepers attack the player. After defeating them, the player goes on the offense and targets the Thorian's neural nodes, there is a little cut scene which shows that the Asari is reanimated suggesting that the Thorian and the Asari are somehow connected with each other. After the player destroys multiple nodes and waver after wave of Thorian creepers and the Asari clone the Thorian crashes down and is "killed'.
An Asari bursts free and thanks the player, although she confesses that she wished the Player had not killed the Thorian. Shepard asks her questions about Saren and the Conduit and she agrees to him the "cipher". It will help the player better make sense of the images. She also gives her back story about how her along with Benezia went to Saren to try and guide him down a gentle path. However, on Sovereign he was all but unstoppable as the ship had an effect on all of them. Soon they found themselves allying with Saren and executing his plans. It is the players choice whether he kill the Asari for her transgressions or let her go so that she can help the colonists that she had harmed. If the player completed the optional side quests then you will find that the power, water and food is restored to the colony. Also, if you used the Thorian gas then the casualties are minimal. The citizens thank you and vow to continue on with their lives
Mass Effect 2
Feros is referenced in Mass Effect 2 on Ilium where Shepherd encounters either a colonist or Shiala, the Thorian Asari slave, if you rescued her. The Colonist/Shiala is on Illium to review a contract with Baria Frontier proprietor, Erinya, in which the Feros colonists agreed to unnecessary Invasive Medical procedures buried in fine print. Shepherd can choose to convince Erinya to accommodate the colonists or ignore the plea in the assignment: Illium: Medical Scans.