It’s a fiercely protected state secret in Israel. No-one dares speculate openly about the identity of an infamous mystery prisoner or even enquire about what he may have done. A blanket suppression order has been issued on The Case of Prisoner X, even after his equally mysterious death in custody. Who was he and what could he have possibly done to be jailed in a super-secure, stand-alone cell in a prison where his guards didn’t even know his name? And what is it about the case that warrants a dramatic, all-points ban on coverage, even hinting that the ban itself didn't even exist. Now, some key answers as a Foreign Correspondent investigation follows a trail from Israel all the way to suburban Australia.