
The Infiltrators investigation takes you to every corner of Atomfall — and there’s a pretty good reward waiting for you at the end. In the starting region, you’ll find a hidden message from a group of Soviet commandos that have infiltrated the Science City. You’ll need to follow their footsteps to see if any are alive and if any of them can help you escape.
Spoiler Alert: They can’t help you escape, but you will find a surprisingly good gun for helping them. If you’re lost and want help progressing the quest, here’s how to complete every step — especially the final step that the game doesn’t explain.
How To Begin The Investigation

From the starting Bunker located in the south of Slatten Dale, go west to find the Helicopter Crash Site at 28.2E, 71.1N. There’s a destroyed bridge leading to Bunker L7 nearby, and past the crash site there’s an entrance to Slate Mine Caves.
There’s a dead body inside the crashed helicopter with a note detailing the location of a cache of supplies. The cache is pretty far away, and reading the note begins the Infiltrators investigation in Slatten Dale.
Where To Find The Supplies

Go northwest to the Railyard in Slatten Dale — it’s found at 28.7E, 77.5 on your map. Look at the edges of the map for faint numbers showing the location. The actual place you’re looking for is a shed at 28.5E, 77.1N, right under the Railyard icon on the map. Crawl through the narrow opening on the garage door to get inside.
Open the locked box to get an extremely useful Sticky Bomb Crafting Recipe. Use this item in your inventory to permanently unlock Stick Bombs for crafting.
- Sticky Bomb: Improvised explosive device, sticks to impact point before detonating.
- Ingredients: x3 Gunpowder, x6 Glue, x4 Scrap
Where To Go In Casterfell

Read the note pinned above the container to find the next step of this investigation. You’ll be sent to coordinates in Casterfell Woods at 27.0E, 90.6N. To reach Casterfell Woods, go to the Sewer Entrance (27.9E, 78.7N) in Slatten Dale. The gate is unlocked.
Entering the sewer, go left to the Main Facility room. There are two Outlaws here. Take the out and progress forward through the gate — you’ll find a sign pointing you toward Casterfell Woods. Leave through the exit to reach the next region of the map.
We need to reach the northeast corner of Casterfell woods. From the red phonebooth, go right until you reach the main road on the coast. Turn left and pass through the tunnel with two Infected enemies. On the other side you’ll find a small house called the Garden Centre.
Go to 27.0E, 90.6N and enter the Cellar behind the two-story building. Down below, you’ll find another Sticky Bomb Crafting Recipe and some other items. Read the notes through the narrow crawlspace, then duck under the doorway that’s been boarded up to collect the “I Can Hear Voices“. This one points you toward the region of Skethermoor.
Where To Go In Skethermoor

To reach Skethermoor, travel through Wyndham Village and use the southeast exit. Skethermoor is a dangerous zone patrolled by Protocol Soldiers with powerful weapons. If you’re following the investigation, you’ll want to go to Brinsop Manor Ruins at 39.6E, 772.N. It’s to the southeast of the Wyndham Village gate and isn’t guarded by Protocol.
At Brinsop Manor Ruins, go through the destroyed building and into the backyard. On the left side there’s a path through the hedges that leads to a cellar. Down below, watch out for traps and you’ll find Ilya Kozlov — talk to him to learn more. He’s the last of the Soviet infiltrators and if you agree to help him, you’ll get a quest to bring him supplies to repair his radio. He’ll request x10 Scrap and x4 Glue.
This is a pretty easy set of materials and many of them are in the cellar. Return and give the supplies and he’ll say he needs time to repair the radio. But this is a lie — if you return to the cellar, you’ll find Ilya is gone.
- NOTE: Squeeze through the narrow space in the center of the Cellar to find two crates. One of them has Training Stimulants.
Getting Your Reward

Return to the underground and you’ll find the cellar is empty. Ilya has escaped to a nearby cave in an attempt to find another way out — you’ll find him at the Secluded Cave in the far north of the map at 41.2E, 79.4N of Skethermoor. It’s directly north of Brinsop Manor.
The cave is full of Infected. Fight to the ramp where you’ll find Ilya’s dead body. He’s carrying Ilya’s Key and the powerful Falkirk Battle Rifle (^Stock). This is an extremely useful Assault RIfle at this point in the game and you won’t want to miss it.
There’s also a useful Modified JM-3 Assault Rifle near the entrance. At the water, turn left to find a narrow space where a soldier hid. There’s an automatic pistol and a special assault rifle — both are rusty but in good condition. The Battle Rifle is the real prize here, though.