Katherine inspects a refrigerator in Threshold’s VR/IV lab and is stunned to find a wide range of powerful psychedelics and other illegal substances, including LSD-related diethylamide, psilocybin, DMT, Salvia extract, MDMA, and Rohypnol. She concludes the drugs are being used alongside high-end virtual reality to create extreme dual-stimuli experiences.

Explaining neural plasticity, Katherine tells Langdon that repeated VR sessions intensified by hallucinogens can rapidly and unpredictably alter brain structure. She theorizes Threshold may be attempting to “rewire” consciousness to feel more normal outside the body, effectively tuning a subject toward a dissociated, out-of-body state—an idea that connects directly to her work on nonlocal consciousness.

Katherine worries that Sasha, as an epileptic already prone to altered states, would be an ideal test subject. When Katherine points out the presence of Rohypnol, she suggests Sasha’s reported memory issues could be worsened or even manufactured by regular dosing that causes anterograde amnesia, allowing subjects to function while remembering little or nothing of the sessions.

Langdon and Katherine consider the implication that Threshold might be experimenting on institutionalized patients who would not be missed, including another epileptic man Brigita previously brought from the same institution. Langdon, alarmed, presses to find proof that the CIA is running nonconsensual human experiments, recognizing it would trigger massive public outrage.

They leave the lab and move deeper into Threshold’s maze-like corridors, trying not to lose their bearings. After passing double doors into a cooler, heavily filtered, museum-like dead-end hall, they reach an alcove with an oversized sealed revolving glass door labeled “RTD,” which Katherine interprets as Research and Technical Development, potentially the area they need.