Conceptually, the latest Go Back is broadly similar to the first two outings, following in reverse the journeys of individual asylum seekers. But this time there is a fresh emphasis on the Abbott government's much-touted "turnback" or "towback" policies. McPhee and his team know only too well that the success or otherwise of this style of "constructed documentary" depends on the quality of the participants. An enormous amount of time and money goes into finding just the right mix of human ingredients to make the social experiment fizz and sparkle on screen. Potential participants are rigorously screened and even interviewed by a psychologist. "I want people who are happy to express how they are feeling and express their thoughts and opinions," McPhee says. "There's no point taking someone who just won't speak." Viewers also have a natural desire to see some development in the views of the participants, for them take an emotional voyage that parallels their physical journey.

However, shifting from a long-held political position can often come at significant personal cost. "The psychologist told me that to change your mind is actually a really big deal if that opinion forms part of who you are," McPhee says. "You can put a lot of pressure on your social situation. If you have a different opinion from your family and friends you can be ostracised." One of the participants, Andrew Jackson, a Melbourne teacher, moderates his hardline views significantly over the three episodes. Jackson's mental turmoil and emotionally charged response to seeing conditions in a Jordanian refugee camp and visiting Syria, where they come under fire from ISIS insurgents, is in stark contrast to that of Kim Vuga, a self-described freelance journalist from Townsville. Vuga administers a Facebook page called "Stop the boat people" (motto: "This is Australia: We eat meat, we drink beer and we speak f**kin' English."). Months after the end of filming she posted videos of herself and a small group of friends picketing outside the Townsville offices of federal Member for Herbert Ewen Jones brandishing placards declaring "Refugees suck Aust dry" and "Multicuture (sic) is a failure".

McPhee was under no illusions that Vuga would move far - if at all - from her uncompromising views. Vuga saw the program as a "once-in-a-lifetime" opportunity and a chance to travel outside Australia. "I had to get a passport," she says. "I hadn't been out of Australia. I'd been to New Zealand when I think I was 12. Technically, I really hadn't been anywhere." Vuga confirms that the experience has done nothing to change her mind that asylum seekers are a "threat to our security". Vuga and Jackson were joined by Nicole Judge on their trip to Jordan and Syria. Judge is a high-profile whistleblower who worked on Manus Island and gave evidence to the parliamentary inquiry into the death of Reza Berati.

But Vuga calls Judge a "traitor" in the first of the programs, and was unwilling last week to revise her opinion. "I still see Nicole as a traitor to our country," she says. "Nicole knows this." Meanwhile, relations between Vuga and Jackson were, if anything, even more poisonous. "She is a revolting person," Jackson says. "She is not a nice person." (Vuga describes Jackson as "annoying" and "quite rude".) The pair clash frequently on screen as Jackson begins to question his own views and how much he "deceived" himself in the past.

Jackson now says when he in the past applied labels such as "country shoppers" to asylum seekers he was merely avoiding harsh truths. "I could then put that problem in a little box and close it and not think about it because if you do think about it it's really painful," he says. "I've spent the nine months since the show trying to work out why I have been such a bastard in my life. "We're born in to the lucky country and you have two choices. One is to try to help people - and in some ways you realise that's impossible - and the other is to go, 'I'm feeling guilty about this. How do I not feel guilty about this? I'll somehow make it their fault'." One of the highlights of the series is watching Jackson struggle with his conscience and question some deeply held beliefs.

"Once it started happening in the show, I accepted it," he says. "I could have fought it but that's not then being true to myself or I could go, 'This is happening, it's on TV. Great. You're going to get to watch me change my mind'." Go Back Where You Came From screens on SBS on July 28 at 8.30pm for three consecutive nights