|How to Start:||Complete the quest "The Ice Palace"|
After completing The Ice Palace, return to Lilya Hagen on board the Groundbreaker to finish the latter quest and begin this one. Apparently after all your work for her, Lilya has decided to be honest with you, revealing that she believes aliens are the explanation for the experiments you found in the labs on Monarch and on board HRS-1084. Well, she went from zero to crazy awfully quick. Still, she pays well, so indulge her and she'll task you with traveling to Byzantium and killing Dr. Chartrand, whom Lilya believes is collaborating with the aliens.
Travel to Byzantium and make your way up to the Estates District and enter a house to the northwest of the stairs leading to the Acropolis District. With the Byzantium Estate Key that Lilya Hagen gave you, entry shouldn't be an issue, and inside you'll find that being a Board scientist of questionable morality makes for a pretty swanky lifestyle. Loot around the house if you care to - the items you'll find aren't really worth mentioning and are technically stealing, but nobody is around to catch you - then head into a room to the southeast and use a terminal and open up an elevator by picking the options [Laboratory Access] and [Unseal Entrance]. You can also read some logs, which seem to lend a bit of credence to Hagen's paranoia.
Exit this southeastern room and return to the large central chamber, then head east to find some now-unlocked doors leading to an elevator. Ride down and go through some doors to the west to come face to face with a rather accusatory Dr. Eva Chartrand. At any point in this conversation you can choose the option to [Attack], which is what Hagen wants. Chartrand isn't alone, however, as some corporate troopers and automechanicals comprise her security detail, but using the cover of the doorway should be sufficient to secure victory. Once Chartrand is dead, you can loot the lab, leave, and return to Hagen, who will reward you with 2,188 Bits and the unique SubLight VP Armor, completing the SubLight questline.
Alternatively, you can hear Chartrand out, who will inform you that it's not aliens that threaten the Halcyon colony, but malnutrition. For whatever reason, the food sourced on Halcyon isn't giving enough nutrients to sustain the colony, and unless something changes, the colony faces slow starvation. Logically one would assume that perhaps the food should be changed, but the Board and Chartrand are instead set on changing humans, splicing them with raptidons to hopefully make them capable of surviving on the food native to Halcyon. Given the scientists you've found in suspended animation attest to the fact that the Board is nowhere near a solution, and something about making human/acidic death lizard hybrids doesn't seem like the best idea at any rate.
During the conversation you can pass a [Lie 1] check to threaten the well-being of her companions, and a corporate commander will chastise her for sharing Board secrets. You can also find out from Chartrand that the Board has lost critical, irreplaceable military resources in the form of the assault cruiser Cornelius Vanderbilt. Perhaps the Board's stranglehold over Halcyon is far more feeble than it seems? In any event, so long as you don't start a fight you should reach a decision - you can ask your companions for advice, but ultimately your options boil down to asking Chartrand to switch allegiance to Phineas , allow her to keep working for the Board, or... well, you can still always just kill her. Killing troopers or causing Chartrand to defect to team Phineas will, of course, result in negative Board reputation.
Whatever decision you make (assuming you didn't resort to violence outright) the corporate commander here still has a say in matters, and he's not keen on letting you walk out with such damning information. Either pass a [Persuade 100] check, bribe him (this cost us roughly 2,500 Bits) or say "Sophia needs me alive.", presumably only an option available if you've progressed far enough along the Board's main questline (at this point in time we had everything done up to Kept Secret But Not Forgotten).
Note: Seriously consider reading some notes on the northwestern wall, as they contain some of the most substantive details of the crisis facing Halcyon you'll find. Doesn't add anything to gameplay or progress, but for the sake of story and lore, it's nice to know more about why Halcyon is starving. It also lends credibility to Phineas' scheme - the scientists on the Hope might just be the colony's only hope.
Should you leave without killing Chartrand, Hagen will not be pleased when you next talk to her. You'll be unceremoniously fired from SubLight (not like there were any more quests for you after this one anyways), you'll gain negative SubLight reputation, and worst of all, you'll get no monetary reward! This does technically count as completing the quest, however, at least for trophy/achievement purposes.