It's May 1971, and Qantas flight 755 takes off from Sydney on a routine flight to Hong Kong. 

Then a man calls the airline, saying he wants a half a million dollars, or else 'the plane will blow up'.

The public anxiously watch the skies above Sydney, as bomb experts are called in, and the plane's fuel runs dangerously low.

How can someone hold a plane full of passengers to ransom?  

Host Richard Roxburgh takes a deep dive into the events of that fateful day.