Borderlands 4 One Fell Swoop Walkthrough [Step-by-step Guide]

What to know

• One Fell Swoop is the 5th main mission in Borderlands 4, given by Zadra.
• The mission has three major phases: sabotaging Sol’s facility, stopping the airship, then halting the Locust attack.
• You’ll need to use Locust sample grenades to break armored doors or armor of elites.
• There’s a timed escape at the end — once systems are destroyed, you have about 27 seconds to get out.

In One Fell Swoop, you’ll join Zadra to sabotage Sol’s production facility, assault his airship, and stop the impending Locust attack on Outbounders HQ. The mission has multiple combat, traversal, and puzzle moments, so staying alert is key. Let’s go phase by phase.

Phase A: Sabotage Sol’s production facility

Step 1: Reach and enter the facility

Talk to Zadra in her lab to start the mission.

Follow the quest marker to Sol’s production facility. When you reach the gate, wait for it to open. Be ready: tough enemies spawn.

Step 2: Clear interior & hack systems

Proceed inside, eliminate all guards and enemies in the first halls.

Go to a “synth processor” in the next area. There’s a core behind openings—shoot the core to damage/destroy it.

After system damage, return to Zadra in the lobby. You’ll then use an elevator (with her) to reach the next area (towards the airship).

Phase B: Infiltrate the airship

Step 1: Breaking past armored doors

After meeting Zadra, you’ll arrive at an armored door. Guns won’t work. Instead, find a vent above. Enter via the vent, drop into the lab behind the door.

In the lab, clear enemies, then find the Locust sample dispenser.

Get an explosive sample and throw it at the armored door to blast it.

Step 2: Defeat Bio-bulkhead and Reach the Airship

Return to Zadra, and go deeper. You’ll reach a boss arena with a Bio-Bulkhead. Use Locust samples in that arena to disable its armor briefly (so you can damage it).

Kill the armored brute/boss, then climb ladders, use grappling or vents to reach the airship itself. But you do not board the airship here.

Phase C: Stop Sol’s Locust attack

Step 1: Return to Outbounders HQ & help Rush

After the airship sequence, teleport (or be brought) back to Outbounders HQ. Find Rush (who’s in danger) and help him by clearing enemies. Be cautious of corrosion/environmental hazards.

Head to the fast travel station inside the HQ bunker "The Launchpad". Remove debris using your grappling hook. This lets you reactivate the station. And Zadra is again your companion

Step 2: Enter the airship from the HQ & destroy systems

Exit the bunker. A tractor beam from the airship will lift you up — stand in it to reach entry.

Inside the airship, locate a terminal and eject thermal capacitors.

Then, destroy three critical systems around the ship (objectives). After the last system is destroyed, a countdown begins (about 30 seconds). Escape quickly via the same hole/exit path you used to enter.

Mission ends here.

Rewards, drops (expected) and achievements

• Legendary items from Bio-Bulkhead can include: Waterfall (grenade), Budget Deity (weapon/shield), Sho Kunai (throwing knife).
• Cosmetic and Eridium drops are always random and may vary per run.
• The “One Fell Swoop” achievement/trophy is unlocked upon mission completion.

Strategies to keep in mind

Wrap-up: completing One Fell Swoop mission

When you manage to eject capacitors, destroy the three critical systems, and escape within the time limit, the mission completes. You’ll receive XP, money, Eridium, a rare sniper rifle (blue/purple) and the “Devourer” weapon skin.