Langdon and Katherine enter a subterranean operating room in the CIA’s Threshold facility and confront a ceiling-mounted robotic surgery system positioned over a strapped-down surgical bed. The restraints and cranial immobilization screws unsettle Langdon, while Katherine recognizes the setup as far beyond routine implant work.

Katherine examines the equipment and concludes it is designed for deep-brain procedures—tumor removal, aneurysm work, or precise tissue extraction—rather than the comparatively simple placement of epilepsy-related RLS chips. When Langdon mentions Sasha Vesna’s skull scars and “minor complications” during her chip procedure, Katherine worries Sasha may have been used as a compliant test subject for more invasive experimentation.

Finding no obvious proof to document, they leave the medical suite and move deeper into Threshold, entering a foam-insulated room labeled “Immersive Computing.” Inside, they find eight gimballed reclining chairs with advanced VR helmets, suggesting high-end simulations synchronized with motion and sound.

At a terminal, Katherine explains how VR can create “presence” and recounts a formative Princeton experiment that produced a powerful illusion of being outside her body, reinforcing her interest in nonlocal consciousness. The terminal is password protected, preventing them from seeing what simulations are being run.

Katherine then spots, through a locked glass-walled computer room, IV stands and a refrigerator stocked with pharmaceuticals—evidence that Threshold is combining intravenous drugs with VR, a potentially brain-altering dual-stimuli protocol. Needing to identify the drugs, Langdon smashes the window with a metal chair, reaches in to unlock the door, and opens access to the secured room.