Citadel: Leviathan

Acquisition
Complete Citadel: Dr. Bryson.

Walkthrough
Investigate objects in Dr. Bryson's Lab for clues. First, check the audio log on the table next to EDI, which leads to the galaxy map search program. As you explore the lab, certain objects will supply search filters to use on the galaxy map program to narrow down the location of Leviathan.

A complete search of the lab will turn up six different filters: Blackout Crimes, Creature Sightings, Rachni Activity, Locations with Element Zero, Prothean Activities, and Reaper Activities. Only one filter needs to be selected for Shepard to be able to leave the lab and explore possible Leviathan sites around the galaxy, but you can opt to use additional filters to tighten the search. Using the Creature Sightings, Locations with Element Zero, and Reaper Activities filters simultaneously will pinpoint the correct location; the Blackout Crimes, Prothean Activities, and Rachni Activity filters are irrelevant and will confound the search, so keep them disabled.

While searching the lab, be sure to collect the weapon mods: the SMG High-Velocity Barrel, Pistol Cranial Truama System, and Pistol Ultralight Materials are located on the balcony outside the lab, while the SMG Mass Pulse Recoil System is on a shelf in the second room.

With the investigation complete, depart the lab and begin the next mission.