Side Story · Underpass
Zoe HandoffMaintenance Protocol
Respond to an Oldest House alarm, repair three malfunctioning bulbs, and survive the final projector sequence.
- Side Story
- Zoe Handoff
- Requires
- Zoe's Briefing
- Triggered at
- Central · Watchtower
- First destination
- Underpass · Deepest Underpass
- Reward
- Standard Issue Coverall
- Field repairs
- 0 / 3
- Final procedure
- Repair the three field bulbs
- Electrosensitive BulbCondition not cleared
- Volatile BulbCondition not cleared
- Botanophobic BulbCondition not cleared
Three independent repairs, then one final projector sequence.
Quick answer
Talk to Zoe at the Central Watchtower to start Maintenance Protocol, then fast travel to the Deepest Underpass and enter the Oldest House's lower section. Watch the projector briefing, activate the switchboard to reveal the bulb coordinates, then fix all three field bulbs: remove the power around the Electrosensitive bulb, calm the Volatile bulb through its dialogue and Hiss fight, and destroy the Mold around the Botanophobic bulb. Return to the Projector Room, take the slide sequence, and choose Break the bulb to finish.
Field repairs0 / 3
How to start Maintenance Protocol
Maintenance Protocol starts automatically when you finish the Zoe conversation at the Central Watchtower. There is no separate quest marker to accept, and no trip back to a board.
Central · Watchtower
- Requires
- Zoe's Briefing
- First destination
- Underpass · Deepest Underpass
New Growth unlocks from the same conversation, but it also has a second way in. Zoe's Briefing is a hard requirement for Maintenance Protocol only.
The alarm is the quest handoff, not a separate encounter. Your first real move happens in the Underpass.
- 1Complete The Hedron Link and let Zoe's Briefing start.
- 2Go to the Central Watchtower and talk to Zoe through the whole conversation.
- 3The Oldest House alarm triggers and Maintenance Protocol becomes active in Side Stories.
Do not search Central for the entrance: the alarm points at the Oldest House's lower section, which you reach from the Deepest Underpass fast travel point.
Open the Oldest House routeQuest at a glance
- Type
- Side Story
- Main zone
- Underpass
- Main POI
- Oldest House lower section · Projector Room
- Requires
- Zoe's Briefing
- Repairs
- 3 field bulbs + 1 final bulb
- Reward
- Standard Issue Coverall
Maintenance Protocol walkthrough
Five phases: get in, unlock the bulbs, repair the three field bulbs, return to the projector, and escape the slides.
Enter the Oldest House
Leave the Watchtower, drop into the Underpass, and open the sealed Oldest House entrance.
- Fast travel to Deepest Underpass and head south from the fast travel point.
- Climb the ledge, reach the sealed door, and use the access sequence to open it.
- Inside, clear the Mold encounter and follow the passage south toward the stairs.
Look for: The lowest Underpass level and the sealed door with its intercom.
From the Deepest Underpass fast travel point, follow the route south, climb the ledge and reach the sealed Oldest House door.
- 1Fast travel to Deepest Underpass.
- 2Head south from the fast travel point and climb the ledge.
- 3Reach the door, use the keypad or intercom interaction, and go inside.
The Oldest House access code is the Morse word IN: dot, dot, dash.
- Morse word
- IN
- Morse sequence
- •• —
The access sequence spells IN as dot dot dash. The exact keypad and intercom wording is still being checked against production interaction data, so treat this as the verified answer rather than a field name.
The lower section opens with a Mold encounter before you reach the projector area.
This is a normal combat gate, not a boss. Clear it and continue south through the passage.
Power Upgrade
A Power Upgrade sits near the entrance route. It is a normal pickup, not a quest objective.
Find the Bulb Coordinates
Watch the maintenance film in the Projector Room, then activate the switchboard to reveal the bulbs.
- Enter the Projector Room and start the maintenance film.
- Let the projection run to the end instead of walking out early.
- Interact with the switchboard to place all three bulb coordinates on your map.
Look for: The projector screen and the switchboard beside it.
The Projector Room is where the quest turns into three repairs: watch the maintenance film, then use the switchboard next to it.
- 1Enter the Projector Room and start the maintenance film.
- 2Wait until the projection finishes; leaving early does not reveal the bulbs.
- 3Interact with the adjacent switchboard to reveal the three field bulb coordinates.
All three coordinates are in the Underpass, so you never need to leave the zone.
If you travel to a bulb before the switchboard, the objective may not be active yet.
Repair the 3 Field Bulbs
Three bulbs, three different problems. They are independent, so fix them in any order.
- Electrosensitive: remove the nearby power before it will accept a repair.
- Volatile: talk to it, clear the Hiss, talk again, then repair it.
- Botanophobic: destroy every Mold growth around it, then repair it.
Look for: Electrical power, a panicking bulb, and Mold growth.
Once the switchboard reveals them, the three field bulbs are independent. Fix them in any order.
Public routes list the bulbs in different orders. That is route optimization, not a gameplay dependency, so the quest never forces a sequence.
Electrosensitive Bulb
- Player rule
- Remove power
- Location
- Underpass · directly below the Research Stations fast travel door
- 1Find the power sources in the bulb's immediate area.
- 2Move or remove all three so no active power remains.
- 3Interact with the bulb to repair it.
Active electrical power is still in the bulb's immediate area. It will not accept a repair while a nearby power source is live.
Solver: Clear all three nearby power sources, then interact with the bulb to repair it.
- Power source 1 cleared
- Power source 2 cleared
- Power source 3 cleared
Public guides describe this differently: some move the nearby Charges into lower inactive cores, others move the batteries away from the bulb. The reliable player rule is the outcome, not one specific object route.
Clearing the condition is not the repair. You still have to interact with the bulb afterwards.
Volatile Bulb
- Player rule
- Calm and defend
- Location
- Underpass · Halfway Trail, east of the fast travel door
- 1Talk to the bulb and start reassuring it.
- 2A Hiss encounter spawns: clear it while the interaction stays active.
- 3Talk to the bulb again and finish the dialogue.
- 4Interact with the bulb to repair it.
- You're okay.
- I'll keep them away from you.
- You deserve to be fixed.
Follow the reassuring path in order: talk first, fight when the Hiss arrive, then talk again. Public guides word the middle line slightly differently, so use the reassuring option rather than one exact English sentence.
Your dialogue options use the game's own localized strings. This page only tells you which answers keep the repair moving.
Talk to it first, clear the Hiss that spawn, then finish the follow-up conversation before you try to repair it.
Clearing the condition is not the repair. You still have to interact with the bulb afterwards.
Botanophobic Bulb
- Player rule
- Clear Mold
- Location
- Underpass · Mold-covered island north of the Research Site
- 1Destroy every Mold growth around the bulb.
- 2Check behind the bulb and the surrounding walls for stragglers.
- 3Interact with the bulb to repair it.
- Visible Mold growth
- Remaining fungal growth and spores
If the repair prompt never appears, there is probably one more Mold growth behind or beside the bulb rather than a broken quest.
The bulb is surrounded by Mold growth and will not accept a repair until every piece in its immediate area is destroyed.
Whether you should eat Mold is a different question with its own page. This section only covers clearing Mold around the bulb.
Search the immediate platform again, including the wall and floor growth around and behind the bulb, then interact with it.
Clearing the condition is not the repair. You still have to interact with the bulb afterwards.
Return to the Projector
With all three repairs done, head back to the Projector Room for the final procedure.
- Fast travel to Deepest Underpass and re-enter the Oldest House.
- Return to the Projector Room you visited during the briefing.
- Interact with the projection to begin the final sequence.
Look for: The Projector Room and its light bulb interaction.
- Electrosensitive BulbCondition not cleared
- Volatile BulbCondition not cleared
- Botanophobic BulbCondition not cleared
Locked until the field repairs are done
The final bulb belongs to the projector sequence rather than the open world, so do not go looking for a fourth bulb in the Underpass.
The final bulb is part of the projector sequence, not a fourth collectible in the world, so it never appears in this count.
Escape the Slides
You are pulled into a slide sequence. Follow the dialogue to its only completion.
- Answer the sequence in order to keep the interaction moving.
- Break the bulb when the option appears.
- Leave the slides once the sequence ends to complete the quest and collect the Coverall.
Look for: The unstable bulb inside the projection.
With all three field bulbs repaired, return to the Projector Room and interact with the projection. You are pulled into a slide sequence that only ends one way.
- 1Where are you going?
- 2Unstable bulb.
- 3Do you know a way out?
- 4Break the bulb.
Break the bulb is the option that ends the sequence and completes the quest. The other answers are there to fill in the story.
- Return route
- Fast travel to Deepest Underpass, re-enter the Oldest House, and go back to the Projector Room.
There is no symbol puzzle and no ability gate here. The finale is a dialogue path, and the escape only resolves once you break the bulb and leave the slides.
As with the Volatile bulb, your options use the game's own localized strings. This page only names the sequence.
Saved in this browser only. It never reads your game save.
Reward
Maintenance Protocol pays out once, when the slide sequence ends.
Standard Issue Coverall
- Type
- Outfit
Maintenance Protocol pays out once, when the slide sequence ends.
The Standard Issue Coverall is a cosmetic outfit. The outfits catalog owns the full list, so this page does not publish a separate outfit URL for it.
Browse outfitsMaintenance Protocol troubleshooting
Where are you stuck?
Finish The Hedron Link and the whole Zoe conversation at the Central Watchtower. Maintenance Protocol starts at the end of that briefing and appears under Side Stories.
What to do next
Maintenance Protocol is a direct child of Zoe's Briefing, so the natural next stops are the briefing itself and the zone you just cleared.
- OpenNew GrowthThe other quest unlocked by Zoe's Briefing
- OpenZoe's BriefingThe handoff that unlocks this quest
- OpenExplore the UnderpassMap the zone, fast travel points and nearby quests
New Growth unlocks from the same conversation and is the other half of the Zoe handoff.
Ask about the door code, a specific bulb, or the projector finale, and the assistant already knows which repairs you have left.
- How do I start Maintenance Protocol?
- What is the Oldest House door code?
- Why won't the Electrosensitive Bulb repair?
- What do I say to the Volatile Bulb?
- Why won't the Botanophobic Bulb repair?
- How do I escape the slides?
Maintenance Protocol is an Underpass side story and the direct child of Zoe's Briefing. It owns the Morse access sequence, the three field bulb repairs and the projector finale, all as anchors on this one URL.