Find and speak to Liara at Apollo's Cafe in the Presidium Commons during your second (or later) visit to the Citadel. She tells you to contact Barla Von regarding a mercenary group that can be recruited. He is located behind the counter at Presidium Commons Bank. Talk to him for more information. Note that you will not see the mission on your journal until you talk to Barla Von.
Proceed to the Krogan DMZ and travel to Dranek. Scan the planet Rothla to find the Shadow Broker Wet Squad, a valuable War Asset. Once you have procured the War Asset, travel back to the Citadel and speak with Barla Von to complete the mission. Completing this mission gives you 5 reputation and 120 experience.