You will have to go back to your hideout and use the laptop to begin The Lair. Head to the main HQ marked on your map. You should reach the location presented in the picture. There are rocks on the right that you can climb. You should do it, as it's a perfect spot to begin the infiltration. Use your drone to scan the area. You will have to tag four soldiers but there are more of them in the area. Draw your attention to the highest construction - a sniper is hiding there.
First, eliminate the soldier scanning the area - he is located in the highest watchtower. From there, you can access stairs that will take you to the highest spot in the location. This will allow you to eliminate the hostile sharpshooter.
While infiltrating the facility, you will have an opportunity to pick your first collector's weapon - M21 SWS. It's in the building marked with a question tag. To be specific, it's in the basement. There are also explosives that will come in handy during your next mission. If you didn't clear out the facility, you will have another chance during a one of the side-ops Clear Out.
There are three enemies by the tunnel and it would be wise to eliminate them. Wait for the armored soldier to hide behind the booth on the left, and kill him. The remaining two enemies are by the entrance. Another soldier is in the very tunnel, and he will be looking at the entrance. Don't hesitate to take care of him. Now, use the CCTV server and gain access to security cameras.
The alarm will go off and you will have to use the air shaft in the next room. If you are in the middle of Clear Out, you will have to plant explosives that you collected from the barracks previously. The map will mark the right these three places. Escape through the air shaft and exit the area to complete your mission.
Unlocked reward that can be purchased for completing the mission:
- Herstal Flashlight - Flashlight
- Herstal IMZ Ironsights - sight
- Gas Grenade - Gas Grenades
- .338 AP - Ammo
- Herstal Laser sight - Laser sight
- Herstal Silencer - Silencer
- Herstal Scope - Scope
- Leafy Humus - camouflage
- Herstal - assault rifle