In a Canberra court room one of the most controversial trials ever to be held in Australia will soon get under way. The case is highly sensitive, with key evidence central to the allegations unlikely to ever be heard by the public. A former spy and his lawyer have been charged with conspiring to reveal secret information relating to an Australian intelligence operation aimed at a friendly foreign government. On Monday Four Corners investigates the extraordinary steps the Australian government has taken to prosecute these men and to keep them silent.