She was to become the public face of a campaign to prevent Lake Pedder from being flooded for a hydro-electric scheme. In 1972, she set off for Canberra in a 1930s Tiger Moth to lobby politicians and write "Save Lake Pedder" in the sky above Parliament House. The plane never arrived, and its wreckage was never found.
For the past 36 years, the mystery of what happened to Mrs Hean and her pilot, Max Price, has haunted Tasmania. Now the writer and film-maker, Scott Millwood, has uncovered new evidence supporting the theory that the aircraft was sabotaged in order to silence her. The vintage two-seater was last seen off Tasmania's north-east coast. Before Mrs Hean left Hobart, an anonymous caller telephoned her with a sinister question: "How would you like to go for a swim?" The plane's hangar was broken into the night before the flight, and its emergency beacon was later found hidden behind fuel drums. Yet police dismissed the possibility of foul play, and only a cursory search was made for the Tiger Moth. With no bodies recovered, there was no inquest. The state government, an enthusiastic proponent of hydro-electricity, resisted calls for a public inquiry.