After his recovery, Primarch Adrien Victus asks Shepard for assistance in retrieving his son and his missing platoon on Tuchanka. The Primarch laments that he cannot go into detail about the mission, but begs Shepard that the mission is of utmost importance and an extremely delicate political matter.
Should Shepard decide to help, and Garrus is brought along for the mission, Shepard learns through Garrus' insight that it is likely that Tarquin's father promoted him without merit, a dangerous and frowned upon act in turian culture.
Once Shepard reaches Tarquin, he laments that his platoon has been decimated and casualties are staggering. He feels great guilt knowing his comrades' deaths are ultimately his fault, as he tried to mimic his father by employing clever tactics rather than brute force.
He wanted to circumvent the enemy by moving through narrow ruins, as a head on assault would have guaranteed casualties. When spotted by Reaper ground forces, however, there was no room to maneuver and the platoon was subsequently shot down. As a result, his attempt to avoid casualties incurred more, for which he accepts full responsibility.
With his failure weighing heavily upon him, along with the anger of his men, he claims he cannot continue his mission, which was to prevent Cerberus from detonating a bomb that was planted in the Kelphic Valley by the turians after the end of the Krogan Rebellions. It was intended to be a last resort weapon, should the krogan rise up again. Should Cerberus detonate it, an all-out war between the krogan and turians would ensue.
Shepard ultimately convinces Tarquin that he must fulfill his duty, which he agrees to if Shepard will bolster his assault on the Cerberus controlled bomb.
Handling the bomb
Should Shepard decide to assist in deactivating the bomb, Tarquin asks Shepard to cover him while he disarms it. After attempting to disarm the bomb he discovers that an error will prevent him from disarming it conventionally. He climbs up and around the bomb to remove the detonator manually. Most of the locks holding the detonator in place are successively unlocked but one stalls. After a moment of contemplating he realizes that the only way to remove the final lock would cause him to go with it. He climbs down the side of the lock and begins removing the parts keeping it in place. Shepard looks up and sees him dangling with the final part of the lock waiting to be removed. As Shepard yells at him he replies "victory, at any cost," and removes the final piece keeping the lock in place. The lock falls off taking him with it, Tarquin thus sacrificing himself to see the mission complete.
Despite his bravery and sacrifice, Garrus, if brought along, comments on how his completion of the mission would simply be expected by other turians, noting that "we're a hard bunch to please," but also comments that "he never hesitated," and "whatever he was before, he'll be remembered for this."
Back aboard the Normandy, Shepard will talk to the Primarch about his son's death. The Primarch feels great sorrow, and regrets that he had not been completely honest sooner. Primarch Victus expresses pride that his son died a hero with the respect of his men, as much as any turian father could hope for, and gratitude that Shepard gave Tarquin a chance to redeem himself.