This paper endeavors to explore the ISIS prison system, the arrest or abduction, interrogation and confession and total detention processes, as well as the condition of detention facilities, and the physical and psychological torture taking place within the terrorist organization’s jails. Fifty-five ISIS cadres (defectors, returnees or prisoners) and 17 Syrian civilian interviewees who had been detained by ISIS were interviewed regarding their knowledge of and first experiences of incarceration in ISIS prison facilities. Their reports are compiled and dissected into three phases: 1) abduction/arrest, 2) initial processing including interrogation and confession phases, and 3) post interrogation processing….