In this game our main mission is to unite humanity and aliens of the galaxy in order to stop the reapers( godlike machines that come every 50000 years and wipe out all intelligent civilizations.)
In last part we cured the genophage(a biological weapon created by salarians and deployed against the krogans by the turians. It made most krogans infertile). After that salarian Councilor told us that she wants to speak with us on Citadel about illegal activities of human Councilor Udina.
In this part we went to the Citadel to meet salarian Councilor. Our pilot Joker tried to get us a permission to land but no one was responding. After that we got an emergency call from our friend Thane. He told us that Citadel is under attack of the Cerberus(pro human terrorist group). Also he Thane got separated from Ashley(another former member of our crew). Ashley is trying to protect the Council and Thane tried to retake Citadel's security headquarters. We landed near the headquarters with a shuttle and started fighting Cerberus. After that we met with commander Bailey he helped us find salarian Councilor. Then we finally located her she was about to be executed by Cerberus assassin. Councilor told us that Udina is behind this Cerberus coup attempt. At the same time Thane come in and started fighting the assassin. At first they were even but Thane was already at disadvantage- he was terminally ill. The situation got worse when assassin stabbed Thane and escaped. We told Bailey to take care of Thane and chased the assassin. We were not able to slay him but we managed to find the rest of the Council before him. Council were protected by Ashley and Udina was leading them all to be slaughtered. We convinced Ashley that Udina is the traitor working for Cerberus. Udina still tried to open the door and let in Cerberus assassin but we shot and killed him. After commander Bailey came in and confirmed to the Council that we saved their asses. Politicians promised that they will not forget this. But I still don't trust them.
After the Coup was prevented we spoke with Bailey and he told us that Thane is in the hospital. We went there to visit our friend Thane. Doctor said that his wound worsen his Thane's illness so he is dying. We also met Thane's son Kolyat who came to visit his father as well. With his last breath Thane wished that we would be healthy and succeed. After that Thane died. Then we went to a Purgatory club and were reunited with our lover Jack. She informed us about progress of her students who we saved at the Academy. After that we went to see a batarian terrorist. He was badly injured but tried to claim that we are murderer as well. We told him that we only did what was necessary to save the galaxy. After that batarian asked us to shut down his life support. We did that. Anyway even after defeating the Coup attempt by Cerberus we only achieved bitter victory. We lost a good friend Thane and Cerberus attack on Citadel was final insult. From now on we will hunt down and slay all Cerberus agents we will meet. And one day we will take Illusive Man's(leader of Cerberus) head as a trophy.