Langdon and Katherine enter the RTD facility and pass through an antechamber designed for decontamination, then step into a blindingly lit white clean room filled with covered instruments and powered-down computer systems.

As they explore, Langdon notices an adjacent biology lab through glass, including an unfamiliar isolation device composed of many long glass vials fed by thin tubes, suggesting something is being cultivated in suspension. Katherine then shows Langdon a photolithography machine and silicon wafers, confirming the facility can design and fabricate custom computer chips.

Katherine hypothesizes the chips are intended for brain implants, reframing the “robotic brain surgeon” as an implantation tool rather than a sampler. Langdon connects this to Sasha’s treatment and fears Gessner may have implanted a more advanced device under the guise of an epilepsy RLS stimulator—one that could control seizures while enabling other unknown functions. Katherine concludes Threshold appears to be scaling up, but notes the lab’s existence alone is not overtly incriminating.

Pressed about how this relates to her missing manuscript, Katherine explains she only mentioned brain implants in a speculative final chapter. Building on her GABA research and her belief that the brain acts as a receiver, she posited a hypothetical implant that could regulate GABA to lower the brain’s filters “on demand,” widening human perceptual bandwidth to access more of a proposed universal consciousness field.

When Langdon suggests the CIA might already be building something like her idea, Katherine insists her concept is not currently buildable because it would require total integration with the brain’s vast synaptic network. She says the key missing component would be a nonexistent “nanoelectric biofilament,” essentially an artificial neuron, and argues such structures would have to be grown. Langdon then points her back to the biology lab device, suggesting Threshold may be cultivating exactly that.