UNC: Asari Diplomacy

An asari diplomat asks you to rescue her sister Dahlia from a mercenary group in the Macedon syetem, of the Artemis Tau cluster.

Acquisition
After completing a main plot world, visit the Citadel. Sometime after leaving, you will receive a communique from Nassana Dantius upon entering a star system. Go back to the Embassy Lounge on the Presidium and speak with her for details.

Alternatively, you can get information on the mercenaries from Tartakovsky's log files on Noveria.

It is also possible to go directly to Sharjila in the Macedon system before being made aware of the mission, with similar results. Afterward you can still speak with Nassana. It should be noted that this can be done at any point after acquiring the Normandy, unlike the aforementioned method of receiving a communique from Nassana.

Walkthrough
Head to Sharjila and make for the exclamation point marked Stronghold on the map. Deal with all the mercenaries in the base and then go up the the back room on the upper floor. Access the console to find out that the asari mercenary you killed was Nassana's sister.

Head back to the Citadel and meet with Nassana again to confront her about lying to you. With Charm or Intimidate you can get her to grant you access to 'prototype asari mods' in addition to your payment. To acquire these new mods, you can purchase the Armali License from Commander Rentola in Virmire: Landing Zone.