Langdon and Katherine enter the upstairs flat and find it illuminated entirely by black lights, with black-painted walls and a few sparse furnishings. Langdon quickly concludes the space likely belonged to Dmitri Sysevich and is unsettled by the idea that Dmitri had direct access to Sasha’s apartment through the shared key.

They search for Sasha but find no sign of her. In the dark bedroom, Katherine lights candles at a small shrine featuring dried flowers and a photo of Sasha, suggesting Dmitri’s fixation on her. A large floor mat and a ball gag initially look sexual to Langdon, but Katherine identifies the gag as a safety device to protect teeth and tongue during an epileptic seizure, implying Dmitri used the room as a controlled place to experience seizures.

Langdon checks the bathroom and finds it oddly equipped: the mirror has been removed, and a shelf holds a hand mirror, palette knife, mixing bowl, white rubber skullcaps, and canisters of UltraMud theatrical makeup. Under the black light, a crumpled skullcap smeared with mud appears alarming at first, but Langdon realizes it is not blood.

On the dirty skullcap Langdon notices a tiny luminescent fiber and, studying it, experiences a sudden “shift in perspective.” He whispers that “nonlocal consciousness” was what Katherine had been right about, then rushes out, insisting they must leave immediately.

Back in the hall, Langdon kneels at Sasha’s door and tries to slide the earlier note under it, but the thick weather stripping blocks the paper entirely. He realizes the note could not have been delivered from outside; it must have been pushed under the door from inside Sasha’s apartment. As Katherine imagines a simple hiding trick in the closet, Langdon rejects that explanation and hints at a far more ingenious hiding place—one that connects to a phenomenon Katherine described in her lecture—and he shows her the tiny item from Dmitri’s skullcap. Katherine recognizes it, and the implication is that everything they believed about the “golem” figure is wrong.