IT IS a story full of complexity and trauma, and largely unknown to a wider audience who view its subject as merely a publisher of classified military intelligence. Yet the teenage years of Julian Assange – now the subject of a gripping film – will again stir vigorous debate.

Underground, the latest political thriller from writer-director Robert Connolly – which had its world premiere at the Toronto International Film Festival on Saturday night – homes in on Assange's troubled upbringing, in an effort to make sense of his present predicament. The embattled WikiLeaks founder, currently holed up behind the walls of the Ecuadorian embassy in London, remains fearful of being extradited to the US for publishing the leaks.

“I knew a lot about the current situation, but had very little knowledge of that period in history,” says Connolly, whose previous political thrillers include Balibo and The Bank (which also both screened in Toronto). “It was something of a revelation to me.”

In Connolly's new film – which is enjoying repeated screenings at the film festival, such is the level of interest – the teenage Assange (played by newcomer Alex Williams) is a quiet but determined computer geek. He has been on the run with his family for nine years, attempting to escape the clutches of an Aryan cult that claims his stepfather among their leading members.