SHORT ANSWER
The Underhill choice does not change your rewards
Dr. Underhill is the subject of New Growth, an optional side quest in Control Resonant. At the end you choose what happens to her. The guides we checked agree that this only changes her fate and the closing dialogue. The Untapped Brass Dusters recipe and the Budding Mycologist trophy progress are the same either way.
That means you can pick on instinct. The harder part of the quest is not the choice but the middle: the lab will not open without a key that is easy to miss, and the three specimens move around the map. The walkthrough below covers both.
How to start the New Growth quest
There are two ways in, and both lead to the same quest. You can reach Zoe's Briefing in the story and speak to Zoe again, or you can go to the FBC Base in The Park and talk to the staff member on the rooftop next to the Fast Travel door.
If the rooftop is hard to reach, restore the elevator power, or take the northeastern sewer route and approach from the street east of the building.
Control Resonant Underhill walkthrough
- Ask about Underhill at the FBC BaseSpeak to the guard beside the Fast Travel door in The Park. This sends you to the researcher's last known location.
- Search her last known locationGo south of the Fast Travel door to a small rooftop campsite. Take her resignation letter and the Level 6 Clearance Keycard from the desk.
- Open her office in Central ExecutiveFast travel to Central Executive, go upstairs, and use the keycard on the Level 6 office door. Take her notes, the welcome letter, and Underhill's Apartment Key.
- Find Underhill in her apartmentClear the Mold blocking the building in the upper part of The Park, go upstairs, and enter the first door on the left. She is near the kitchen. Talk to her, then take the Sewer Lab Key from the nearby counter or table.
- Enter the sewer labLeave, turn left, and enter the underground area between the apartment and the FBC Base. Turn left at the junction and unlock the door. Read the documents and take the Mold Growth Stimulator and the sample tubes.
- Follow the Mold and defeat the three specimensInteract with the white Mold below the lab. It travels through sewers, rooftops, and streets, pausing so you can interact again, and splits into branches. Follow every branch.
- Return to UnderhillGo back to the apartment once the objective confirms all three specimens are down. This is where the final choice happens.
The three specimens
First branch in the sewer
Usually the quickest after the first split. One guide places it in a caged enclosure in the deep sewer cavern.
Park-side, after surfacing
Take the left branch once you reach the surface. It requires rooftop travel, and one guide places it in an underground sewer courtyard.
The one people miss
The remaining Park-side branch, south of the second. It is easy to overlook, so check the objective if the quest will not complete.
Fire, mobility, and the map icon
Fire attacks work well against the specimens. Stay mobile at close range and clear smaller Mold first. Use the cloud-like Mold icon with an exclamation mark on the map, and check floors above and below if the trail vanishes.
The final Underhill choice
When you return, you decide what happens to her. The wording differs slightly between guides, but the three outcomes are consistent.
The FBC takes her away
The Bureau detains Underhill. The quest ends.
She leaves without the samples
She departs with nothing. There is no further effect.
She continues her research
She keeps her work going independently.
Only her fate
Rewards are identical, and the guides we read mention no later content that depends on it.
Rewards and what the guides disagree on
- Untapped Brass Dusters: an artifact recipe. Every source lists it.
- Budding Mycologist: a Silver trophy. One guide says it also requires completing the Carbon Copy questline, so finishing New Growth alone may not unlock it.
- Power Upgrade Point: one source lists a 3/3 upgrade point in the sewer lab.
- Talent Point: only one source lists +1 Talent Point. Treat it as unconfirmed.
Sources also differ on details such as which door in Central Executive is Underhill's office and on how many choices there are. One walkthrough describes no choice at all, which looks like an omission rather than a real difference.
Control Resonant Underhill FAQ
Who is Dr. Underhill in Control Resonant?
She is a former FBC Mold researcher who left the Bureau to pursue a more aggressive approach to the Mold. She is the subject of the optional New Growth side quest, which sends you to find her and the test specimens she has been growing.
How do I start the New Growth quest?
Reach Zoe's Briefing in the story and speak to Zoe again, or talk to the FBC staff member on the FBC Base rooftop in The Park. If the rooftop is hard to reach, restore the elevator power or use the northeastern sewer route.
Does the Underhill choice change the rewards?
No. Every guide we checked that describes the choice says it only changes what happens to Underhill. The Untapped Brass Dusters recipe and trophy progress are the same either way.
Which Underhill choice should I pick?
Pick whichever fits how you want to play Dylan. Because rewards and later content are unaffected, there is no mechanically better answer. If you want to see every outcome, save before the final conversation.
Why can't I open the sewer lab?
You most likely missed the Sewer Lab Key in Underhill's apartment. One wiki calls this the most common reason the lab stays locked. Go back to the apartment and check the counters and tables near the kitchen.
Which weapon should I use on the specimens?
Fire. Two guides say fire attacks work well, and the specimens are Mold creatures. Stay mobile once they reach close range and clear smaller Mold enemies first if the arena gets crowded.
Sources checked
- GameRant — Should you turn in Dr. Underhill ↗
Used for the statement that the final choice only changes what happens to Underhill, and for the reward list (Untapped Brass Dusters recipe and the Budding Mycologist trophy).
- AllThings.how — New Growth quest walkthrough and Underhill choice ↗
Used for the step order, the Level 6 keycard, the apartment and sewer lab keys, the three specimen locations, and the three final options. This is the only source that also lists a talent point.
- CONTROL Resonant Wiki — New Growth quest ↗
Fan wiki used for the two ways to start the quest, the elevator and sewer routes to the FBC Base rooftop, the Sewer Lab Key warning, and the note that fire works well against the specimens.
- PowerPyx — New Growth walkthrough ↗
Used to confirm the start conditions and the step order, and for the note that the Budding Mycologist trophy also needs the Carbon Copy questline. It describes no branching choice, which is why that part of this page leans on the other sources.
- Control Resonant — Wikipedia ↗
Used only for the release date (September 24, 2026) and platforms.