Mass Effect 3 Walkthrough Part 43: Citadel: Cerberus Ciphers, Cerberus Turian Poison, & Chemical Treatment

You will have obtained the Cerberus Ciphers mission from the turian C-Sec officer in the Embassies, who was speaking into the terminal talking about the Cerberus ciphers. He needs them, he will say, to get around Cerberus encryptions that have been put into place in all of the computer systems after Cerberus hacked and attacked the Citadel’s computers. C-Sec can’t know that their systems are truly theirs until these ciphers are found. You will have to wait until you unlock the N7: Communication Hub mission after the Priority: Perseus Veil main story mission. In the Communication Hub mission, search a console marked with codes to find the cipher and return it to the C-Sec officer. As you so often can, you may also purchase the codes from the Spectre console on the Citadel if you miss them during the mission.

You will have found the Cerberus Turian Poison mission in Huerta Memorial Hospital, from the worried salarian doctor in the long side room to the left as you enter the patient ward. Somewhere on the station, a turian general has been poisoned and lies dying. The salarian will be radioing Palaven trying to get help, but with the planet still in the midst of battle, the turians will refuse to send help. One turian, even a general, is just one turian, or so the salarian repeats, defeated. Again, you will have to find the item necessary to complete this mission during another mission. During the Arrae: Ex-Cerberus Scientists side quest, look in the area you first arrive in to find the item on the med-bay next to a familiar face from Mass Effect 2 (or his surrogate, if he didn’t survive Mass Effect 2.) Return it to the salarian doctor to complete the quest. You may also purchase this item from the Spectre terminal if you miss it during the mission.

You will also find the Chemical Treatment mission in the hospital, given to you by another salarian. They will be seeking out a cure to a chemical poison that is decimating patients in their hospital. During the N7: Fuel Reactor side quest, search a PDA on a crate by the start of the mission to get the necessary data. Return it to the doctors to complete the quest. If you miss the PDA during the mission, you can return to the Citadel and purchase the cure through the Spectre terminal.