The episode's central mystery involves the , an ancient text in the Vatican's secret library that causes anyone who reads it to commit suicide.
Upon realizing he is a "simulacrum," the virtual Doctor uses his sonic sunglasses to record the entire experience and emails it to the real Doctor in the physical world as a warning of the impending invasion. The Vault & Missy [S10E6] Extremis
A series of flashbacks explains how the Doctor ended up guarding the mysterious vault under St. Luke's University: Doctor Who S10E6: Extremis - FilmInk The episode's central mystery involves the , an
The Doctor Who episode is a mind-bending sci-fi thriller written by Steven Moffat that serves as the first part of the "Monks" trilogy. It is widely acclaimed for its complex "simulation theory" plot and for finally revealing the contents of the vault. The Simulation Reveal Luke's University: Doctor Who S10E6: Extremis - FilmInk