|Metro Wiki has a video walkthrough for this level, Dungeon. See Dungeon/Walkthrough.|
|“||The chaos of the tunnel was locked away behind the airlock gates. They seemed invulnerable... and at that moment, so did my comrades.||„|
— Level description
This level takes place right after getting off the Armored Railcar from the Dark Star level. Miller, Artyom, Ulman, Vladimir, Stepan, and Boris must take this path in order to get into D6. Inside are lots of storage rooms and pathways that were formerly used to transport weapons and equipment into D6, each section is closed off by massive steel doors, these storage rooms and pathways are littered with skeletons and the air is toxic, so the team must use Gas Masks. Artyom is ordered with protecting Vladmir, if he dies there is no technician to get the missile guidance system working once the team reaches D6. After opening the first door and entering the first pathway flooded with water, the team is attacked by a horde of nosalises, then a second Horde. Upon reaching the next steel door, Boris is ambushed by a nosalis, and is killed. Stepan vows revenge, and the team moves on. Here you can loot Boris' ammo and his scoped VSV.
- Boris cannot be saved, the nosalis that attacks him is invincible.
- If the other member of the rangers is killed, it is considered mission failure.
- The skeleton that Ulman suggests the team "Take as a memento" seems to have had two heads, as there are two skulls next to each other, but only the one skeleton in the area. This two-headed skeleton is replaced by a normal one (still clothed) in the Redux version.
- The two-headed skeleton could also be a reference to the novel as mutants with additional limbs and heads is said to be occupying the Filevskaya line. A Red soldier also jokingly makes a reference to 'the two-headed mutants of the Filev line' in the level Front Line. It may be a reference to the novel Metro 2034 where Hunter and Homer encounter a two-headed monster wrapped in webbing while traversing an irradiated service tunnel to get to Kolomenskaya.
- The first steel door needs to have a breaker panel activated to work (the panel to the right of the door). There are three other panels in the area however, none of which can be activated after the door has been opened.
- One turns on the emergency lights.
- The one on the other side of the door activates something that causes the whole facility rumble and frightens the Rangers. If the player listens closely after the rumbling ends, they can hear for a moment or two the sound of a child's laughter similar to the noise heard in the 'singing pipes'.
- The third one (near the monorail) activates the ventilation fan, kills a nosalis that was hiding in the shaft and drops its limbs through the large ceiling vent. The nosalis in the air shaft is one of the only, if not the only properly gibbable enemy.
- If one stands close to Boris' dead body and looks closely at his eyes, they may actually twitch and blink.
- Ulman says a joke of how it smells even though he cannot smell through his gas mask because of the air filter.