You ride the trap downward into what looks like some sort of lab. The walls are all of poured concrete and metal. This would have looked futuristic, back in the 70s. Right now it just looks decrepid.
There's nothing much in here other than some decontamination equipment, bent and with some of the wires stripped. It doesn't look like it was done by a pro. Either it was done by the previous owner of the house, vandals, or someone from this place before they left. Maybe it was even... something else. Nevertheless, you decide this isn't creepy enough to not press onward. There's a flight of stairs leading down into darkness.