Bart Simpson and an unnamed red-haired boy in a white shirt and red shorts, holding a lit candle, first appear in a long corridor of blue lockers…

What happens

Bart Simpson, in his orange shirt and black-rimmed glasses, and an unnamed red-haired boy in a white shirt and red shorts, holding a lit candle, first appear in a long corridor of blue lockers under bright ceiling lights. They then stand together in a dim pipe-lined basement with a spiderweb and a drip of green slime, the candle-holder glancing sideways and flicking a drop from his fingers, before walking single file down the dark passage. Bart then squeezes through a narrow gap beside a large pale-blue sliding panel in a brick wall, with a stack of books and puddles on the floor and a molecule-like diagram on the wall.

Written by an AI model from frames of this moment, so small details can be off.