I froze on the stairwell when the terminal blinked red and the doors sealed behind me. You can feel the run tightening — three objectives, one life cycle. I’ll walk you through the exact moves that keep that run alive.
Marathon Parasitism 4 contract guide
Observation: Most players treat priority contracts like errands on autopilot.
I treat this one like a checklist with a timer. Parasitism 4 has three linked objectives you must finish in a single run: grab research clearance at Maintenance, extract the Synthsilk Sample in Bio-Research, then hand it to a DCON. Do them in order and you avoid backtracking and those deadly last-minute scrambles.
Maintenance — download the research clearance
Observation: Buildings in Dire Marsh often hide the terminal on an upper floor or tucked behind office desks.
Head to the Maintenance POI in the south of Dire Marsh and enter the main building. Get to the second floor and move south — there’s a small office with the terminal. The image below shows the room and the terminal location so you won’t waste time hunting.
Where is the terminal in Maintenance?
You’ll find it on the office’s inner wall on the second floor. Interact with the terminal to download the research clearance. Expect the doors to lock the moment the transfer completes — the game throws a wave of UESC enemies at the spot. Clear them and the doors open again; treat the encounter like a short, intense skirmish rather than a drawn-out slog.
I recommend using whatever area-denial tool you favor (grenades, turrets, or a hit-scan primary) to hold angles while you move to the Bio-Research POI. Bungie’s level design rewards quick, confident movement more than slow seeking; be decisive.
Bio-Research — extract the Synthsilk Sample
Observation: Laboratories usually give two access options: ladder/breach or the stairs.
From Maintenance, head to Bio-Research. If you approach the green-marked building from the outside you can climb a ladder, break the window and drop in — the dispenser is immediately to your left. If you take the stairs, the dispenser sits on the second floor near the core labs. Interact with the dispenser to pull the Synthsilk Sample.
How do I extract the Synthsilk Sample from my shell?
Interact with the dispenser once you’re in position. You’ll pick up the Synthsilk Sample immediately. Treat the sample like fragile loot — it’s as delicate as a spider’s silk, and losing momentum after pickup invites enemy waves or other players to ruin the run.
DCON — deliver the sample and finish the contract
Observation: DCON units sit at predictable outposts on the Dire Marsh map, usually at POI edges.
There are three DCON units on Dire Marsh; the nearest to Bio-Research is the one by the outskirts of Greenhouse. Open the DCON’s inventory and add the Synthsilk Sample. The DCON will transmit it back and you’ll complete Parasitism 4. If you’ve used an overlay like the in-game map or a third-party marker tool (some streamers use OBS with map overlays), pin the nearest DCON before you leave Bio-Research to avoid wandering.
Finish the handoff and you’re one contract closer to clearing the Sekiguchi series. If you want extra security, run a short-range pulse or leave a small deployable near the DCON to buy seconds against surprise attackers. Community guides on sites like Moyens I/O and tips from Bungie forum threads often show minor route variations; I scan those before I run a new route.
Want to argue whether aggressive clears or stealthier runs net better long-term rewards?