The facility was at one point a highly industrial site, mining Imulsion and having it extracted and processed within its confines. At some point prior to the events of the Lightmass Offensive, however, (presumably after Emergence Day) it had become overrun with Locust, with the raw Imulsion underneath the facility turning the Wretches lambent and volatile.
At some point a group of Stranded came into the factory only to be massacred, leaving only one known survivor; a man hiding in a small room armed with a Gnasher Shotgun. As the Gears arrive, Baird seems to turn the lights on at the most inopportune moment, shocking Marcus and Dom with the mutilated corpses of the unfortunate Stranded. When the man meets the two, he believes them to be a rescue party sent to save them, but he is sadly mistaken and later dies after falling through a rotten floorboard into a maintenance area filled with Wretches while being forced by Marcus and Dom to show the way to the cart control room. After the Gears get out of the carts, there is a man in a hat and beard waving his arms up and down while Wretches rip out his intestines, indicating there was another survivor in the refinery.
- Main article: Lightmass Offensive
As the facility is only seen at night amidst a severe downpour, the actual size of the facility is unknown. It is known, however, that it was an important Imulsion processing facility and had direct access to the vital fuel through the Locust Tunnels. Teetering on the edge of a cliff next to the ocean, the Lethia Imulsion Facility is the furthest that Delta Squad ever travels out of Ephyra, as it is located right on the outskirts of the city.
Most of the early events of Act 3 occur in the facility, as Delta Squad attempt to find a way into the mines below the facility. Whilst searching the place, they come across many Lambent Wretches and corpses of dead Stranded littered across the place. Its intricate system of mine carts lead directly to the main shaft down into the mines and was the path that the Gears took. After deploying the Sonic Resonator at the underground pumping station, the Gears were able to restore power to the pumping station lift and escape outside the facility as the resonator detonated.
The facility was later destroyed along with the entire Outer Hollow when the Lightmass Bomb was detonated to weaken the Locust forces.
- ↑ Gears of War