Locations: Hyperion, Nexus, Tecunis, Zaubray, Anasa, Solimnae, Kadara
This one starts off intriguingly- message from Captain Dunn of the Hyperion that she needs to speak with you on the down-low. Of course, the quest description tells you straight away what's going to happen, but Ryder doesn't know until the meeting with Dunn.
Seems that a medtech, who should be court-martialed to within an inch of his life, smuggled his aunt with pandemic-level virus aboard the Hyperion, then fudged records to slip her into the general populace. You need to track her down before she reaches the infectious stage and wipes out the Nexus and/or the Angarans. Talk to your ex-squadmate Harry in Cryo for the full details.
You can choose to emphasize the need to help her versus the need to stop her, y'know, dooming Andromeda. Either way, start the hunt in the Immigration area by the docks, talking with a helpful turian.
You can then use your scanner to find places where Ruth has been. Just walk around the area looking for ghosts.
In this case they'll lead you to the Vortex. Talk to Dutch and he'll point out a Salarian at the end of the bar that Ruth got chatty with.
He'll send you to a Turian in Ops.
With cause to believe that Ruth has now entered Stage 2 of her infection, head to the docking bay to find Samuel Francouer sitting on a bench near Immigration.
It seems Ruth clocked him and stole the shuttle. Because that's just how easy it is. Luckily the shuttle is damaged and leaking radiation, it should be easy to track. Hop onto the Tempest in hot pursuit- after all, how far can mere shuttle have gotten?
Ridiculously far, as it turns out. The radiation trial isn't even the Zheng He system anymore, it's on the other side of the cluster in Tecunis system.
Scan for anomalies to find the trail, then scan the trail itself for some research data, and the next system to search.
What's that you say? This damaged shuttle piloted by a delusional civilian who's just hopped across the whole cluster couldn't possibly make it to *another* system ahead of the Tempest? Insert hollow laugh here.
Next you'll track Ruth to the Zaubray system. Again you'll scan for anomalies, scan the trail (it's automatically the first anomaly you search for), then zoom back out to the Galaxy map.
Then on to the Anasa system, then Solminae, then Govorkam, and the planet Kadara. Forget Gil & Kallo's bickering about the Tempest's engineering, get me whoever designed that shuttle! In anycase, land on Kadara and head to the navpoint in the NOMAD (if you get an emergency SOS along the way, don't worry; it'll keep). You find the shuttle destroyed, the mysteries of its design forever lost.
Still, despite the fact that it crashed hard enough to be torn in two, Ruth seems to have survived just fine, though she isn't here. Play the Shuttle Cockpit Recorder to learn more.
Turns out she's been kidnapped. Swell. Use your scanner to reveal footprints on the downhill path.
You can walk or drive down the slope to a hostile Roekaar compound.
There's a handful of raiders, sharpshooters, and adhi here, but once you've taken them out, a dropshuttle will arrive with reinforcements.
They're just Raiders, though, so take them out and then enter the lower part of the building. Here you'll find many things to scan, two containers, and a datapad. Absorb all that to reveal the evil plan here.
So- just to recap, you found Samuel Francouer just shortly after he'd been clocked (an hour or less after - he hadn't even been taken to the infirmary yet). You immediately set off in pursuit of the damaged shuttle, using one of the fastest ships in the galaxy, and not only did Ruth beat you here, but the local Roekaar had time to capture her, carry her downhill on foot, study her disease, learn of their own immunity, and concoct a doomsday plan around it, all in the last forty minutes? Those guys work *fast*....
Anyway, when the room's been cleaned out, use the console here to open the upper chamber.
Go back outside and to the upper door. You'll be launched into a cutscene where the Roekaar leader is holding Ruth hostage. You can let him go and put Ruth in stasis for an eventual cure, or give him a hard time, in which case he kills Ruth and you kill him right back.
You get the same meagre AVP award either way, so follow your instincts, but considering how deadly the virus is just in the wild, even the tiniest chance of a weaponized version has to be considered an 'end of the Initiative' extinction-level event. In any event, a few lines of dialogue will discuss what's to be done with Ruth or her body, and the mission ends.
Don't forget to loot the container in the final confrontation room.