I was three rooms from the terminal when the enemy patrol split my route. You can feel the run narrowing—one mistake and the whole Return on Investment 3 contract slips away. I’ll show you how to grab the UESC Comms Security Code in Quarantine without wasting time or lives.
Marathon Return on Investment 3 contract walkthrough
On every run the Quarantine main building draws more traffic than its neighbors — players funnel there like commuters at rush hour.
I’ve cleared this contract early dozens of times for Traxus, and the play is predictable if you focus: the contract has three tasks and all must be done on the same run. Treat the first task, the code download in Quarantine, as the linchpin; miss it and your momentum collapses. Below I break the tasks into tidy steps so you can move fast and stay alive.
How do you download the UESC Comms Security Code in Quarantine?
Find the main building in Quarantine shown above. Head through the front entrance and stay low. The terminal you need sits in a ground-floor room; when you get close a quest marker will pop, which removes guesswork and saves time.
The terminal is a locked safe. Interact, grab the UESC Comms Security Code, and the first tick of the contract is yours.
Where is the UESC Commander in Maintenance and how do you take its credentials?
Approach Maintenance from the south entrance. You’ll see a pink quest marker highlighting the Commander’s position; it’s that simple. Don’t run head-first into melee — pull to height and trade from above where you take fewer hits.
When the Commander goes down, loot the remains for the credentials. That credential pickup is the second box checked on your Return on Investment 3 contract, and it tends to be the cleanest moment of the run.
How do you intercept UESC comms at AI Uplink or Bio-Research?
Pick AI Uplink if you want speed; Bio-Research is fine if you prefer cover. I take the catwalk to the top — use the ladders beside it and climb onto the cables that roof the walkway. The quest marker appears early when you’re in the right spot.
The catwalk is a razor’s edge; from there you can intercept UESC comms without tangling with ground traffic. Grab the item, and the third task finishes — now the contract is complete and Traxus pays out your reputation and rewards.
I use Bungie’s map markers and the on-screen quest prompts to shave time; Moyens I/O’s screenshots above show the exact angles I favor. Run the route once to memorize the turn-ins and the second run becomes automatic. Ready to get the code and make every remaining step feel inevitable?