After the Cerberus invasion of the Citadel, check your email. You will find a message from Primarch Victus detailing a turian cruiser’s ambush by a terrorist group. All evidence suggests that the volus ambassador, Din Korlack, was the one behind the attack. Head to the Citadel and to the Spectre office to find Victus, and use the terminal to start investigating. Using the information you find there, head back into the Embassy.
Speak with the guard standing on the wall to the left of the elevator. He will eventually give you access to Korlack’s office, where you should now go to investigate further. Follow the waypoint to get to Korlack’s office, which will be down by the other offices of officials such as Commander Bailey. Enter the office and listen to the messages on his terminal by examining it. The third message will suggest that a bug has been planted somewhere inside of the office. Search the locations in his office until you uncover the bug. You’ll automatically find yourself in the Presidium Commons area after you collect the bug, hot on the heels of the saboteur.
Enter the apartments area and search each room until you find the volus inside. Speak with Din Korlack to learn about his bounty and his interactions with Cerberus. He will try to barter a deal with you. You will either be able to keep a colony of innocents safe from attack, or you can accept his fleet of bombers as a war asset. You can choose the former to get Paragon points, or the latter for Renegade points and a little bit more help during your final confrontation against the Reapers. If you aren’t collecting many assets, you may want to bite the bullet and accept the war bombers; every little bit helps. If you recruited and won over Zaeed in Mass Effect 2, he will appear briefly in this mission and lend his help to you in the form of a war asset as well, provided, of course, that he lived through the ordeal on the Collector’s home base at the end of that game.