The desolate fortress of history's most infamous drug lord and a battle-scarred ruin in the Middle East contain a violent past; experts investigate the secrets of these mysterious compounds to uncover how they were built and why they were abandoned. This episode is a mashup of S07E09 "Fortress of the Spy," S04E08 "Pompeii's Gate to Hell," and S04E03 "Escobar's Castle."