As you descend towards the salarian homeworld, it will appear for a moment that you have been trapped. The salarian guards will emerge, weapons drawn, and deny you permission to land. At the last second, a salarian scientist named Padok Wiks will emerge and order his men to lower their weapons and take the krogan diplomat into custody. Here, you can either allow the salarians to take the krogan away, accepting that they didn’t receive word of your arrival until just a minute ago, or you can maintain a violent stance and demand access to the laboratory.
After this initial conversation, you will be able to wander freely around the area. You can speak with a few people here, but none of the conversations are particularly meaningful. They will merely serve to give you some context for what you are about to do. Head inside of the lab. Again, you may speak with the various salarian scientist NPCs here to get some context on the situation. Many of the scientists disapprove of what you are doing, necessary as it may be for galactic survival. Head to the elevator in the back of the room when you are ready to head down. Padok Wiks will meet you there and escort you into the basement, where the main research bay is located. As you enter the basement, your allies will point out a group of body bags. It seems that the female krogan have all died, except for one.
If you made it through Mass Effect 2 with Mordin alive, he will greet you here. It seems that he was the inside informant who leaked information of the females to the krogan diplomat. As you proceed deeper into the basement, an alarm will begin to sound. The base is under attack by someone, but you won’t find out whom just yet. For now, you will have to ensure the safety of the last female krogan. Speak to her. You can either reassure her or treat her as just another asset. The krogan diplomat will contact you and demand that you evacuate the female even as you defend the base from attack. Speak with the female again and allow Mordin to transport her up in the freight elevator.
Run back up the stairs to the elevator. Along the way, examine the computers to hear about Mordin’s research and search the shelf on the rear wall to the Assault Rifle Extended Barrel Mod. When you are ready, examine the elevator. The doors will open to reveal an explosive. With the elevator disabled, your only choice is to leave through the smaller door on the opposite side of the room. Enter and climb up the ladder to begin the next section of the level.