I expected to be less than diverted by Fair Game, an insidery tale of US politics, but it not only really grabbed me, it also, worryingly, made me want to join the CIA: all those square-jawed men in blue shirts strutting determinedly round their humming offices, the world's secrets locked in their bullet heads.
The film draws on the book of the same name by Valerie Plame, who was in the CIA but is not a bullet-headed, square-jawed man. She is a glamorous blond woman, played by Naomi Watts, who worked at a senior level for the intelligence agency until, in 2003, the Bush administration decided to blow her cover to undermine her husband, Joe Wilson, a former US ambassador in Africa. Wilson had written an article in the New York Times rubbishing President Bush's claim in his state of the union address that Saddam Hussein had been trying to buy uranium from Niger to produce nuclear weapons. The administration, desperate to change the story from the unravelling case for war, had decided Plame was "fair game".
As well as leaking her identity to journalists, one of whom printed her name in the Washington Post, officials in vice-president Dick Cheney's office spread the story that Wilson had made the information-gathering trip to Niger in 2002 on which his New York Times article was based because his wife had sent him. According to the vice-president's men, it was a "boondoggle", a pointless task that wastes time and money, mainly designed to keep the ex-ambassador busy. Wilson's reputation was called into question; his wife's career wrecked; their lives turned upside down. Old friends were shocked to discover she was a CIA agent; new enemies accused them of being traitors; their marriage came close to collapse.
The film neatly combines the political and the personal: the shocking fact that the public was misled over weapons of mass destruction and the impact that taking on the administration had on one family. Directed by Doug Liman, who made The Bourne Identity, it is a slick thriller, but also a reminder that the US administration fabricated the case for war against Iraq in 2003, and that the human cost of the deception was huge. Unmasking Plame may have had deadly consequences. In a sequence, the veracity of which has been disputed, the film shows her running agents in Iraq who are murdered when her identity is revealed.
Wilson, Plame and their 11-year-old twins have now moved from the Washington hothouse to the more relaxed atmosphere of Santa Fe in New Mexico, from where he calls me for a long conversation about what seeing their lives put on screen has meant to them. "We knew that it would be very difficult to cram a six-year battle into an hour and 45 minutes," he says, "but they did a remarkable job and within the constraints of a Hollywood motion picture. It is an accurate story of our time and the fight that we went through."
Critics of the film say it overstates Plame's seniority within the CIA – a long-running canard introduced in 2003, when supporters of the administration painted her as little more than a secretary – but Wilson says it accurately reflects her responsibilities, which principally concerned combating the proliferation of WMD. Scriptwriters Jez and John-Henry Butterworth tell me that what appealed to them about the story was that the couple were both "completely central to the case for war". Wilson had investigated Saddam's alleged pursuit of uranium to enrich, and Plame had been tracking aluminium tubes that were supposedly bought by Iraq as part of its nuclear weapons programme.
Wilson, played by Sean Penn, is shown as quick-tempered, voluble, egoistical. Did they get him right? "I think perhaps the character of Joe Wilson is shown as being a bit angrier than I am," he says. "I don't think my temper is quite that short, but I understand the need to reduce the character to one or two dimensions. The portrayal of Valerie also perhaps didn't capture her warmth, but it captured her cool and her ability to operate in stressful circumstances."
The film makes great play of Plame's coolness under pressure – the quality that got her into the CIA. "You can't break me. I don't have a breaking point," she tells her husband in the film. She uses the line to reassure herself as her life is falling apart and, exhausted and depressed, she fears that maybe she does have a breaking point. The temperamental differences between her and her husband are clear: Wilson is up for the fight; Plame has to be cajoled into it.
Wilson says that once he had decided to go head to head with the people trying to wreck his reputation and career, he knew he had to give it everything. "I took a strategic decision early on that the only way to deal with these attacks was to be very confrontational. Anybody who knows of my history the last time I was in the public eye, which was when I was in charge of the embassy siege in Baghdad, knows the effect of the strategy we adopted there in getting hostages released."
In 1990, in the stand-off provoked by Iraq's invasion of Kuwait, Saddam had threatened to execute anyone, including staff at embassies, who harboured foreigners. Wilson, second-in-command at the US embassy in Baghdad but in charge while the ambassador was out of the country, appeared at a press conference with an improvised noose around his neck. "If the choice is to allow American citizens to be taken hostage, or [for me] to be executed, I will bring my own fucking rope," he told journalists. The irony of him being rubbished by the administration in 2003 was that, 13 years earlier, he had been lionised by Bush the elder.
Initially, Wilson went through official channels to get the administration to admit the president had been mistaken in his address. "I had no interest in airing my dirty laundry in public." But when that failed, he went public. As the film makes clear, Wilson was not a professional agitator, or even ill-disposed towards the administration. He had worked for President Clinton as an adviser on Africa in the 90s, but came from a "proud Republican family" in California. He was an establishment man, but with a subversive streak – he likes to say he studied "history, volleyball and surfing" at university. Above all, reflecting his forebears' politics, he was a constitutionalist, suspicious of overarching executive power and horrified that the president could make false claims which, even when they had been exposed as bogus, were left on the record. He believes he knows why his wife was targeted. "It became clear to me early on they wanted to send a signal to the intelligence community, which was beginning to leak stories about how they had been pressured to draw certain conclusions to back up the claims about weapons of mass destruction. The message to them was: 'If you do to us what Joe Wilson just did, we will do to you what we just did to his family.'" He says that when his wife was outed as an agent, the leaks stopped immediately.
Once he began his fight, he was not prepared to back down. "It was not an act of enormous moral courage so much as an act of survival against everything they were throwing at us. At the end of the day, if you don't have your good name, what do you have?" Plame has said it is difficult for her to watch the film. How does he find it? "There are parts of the movie that are very painful," he says. John-Henry Butterworth recalls sitting next to them at a screening. "I thought, 'I wonder if they'll like it', because it touches on some really personal stuff and goes into some uncomfortable areas. I was half watching the film and half trying to gauge how it was going down with them, and there was a moment when Joe reached across and grabbed his wife's hand and she grabbed his hand, and they just sat there clasping hands watching the film for the next five minutes. It was so moving. You suddenly realised that this was real for them; this was something that happened to them."
Wilson is proud he was able to withstand the firestorm that followed his article. "They didn't understand my background in fighting with assholes," he says with the self-confidence – or is it self-satisfaction? – Penn sets out to capture. Wilson has no qualms about having written the article. "It was important for Americans and historians to understand the extent to which procedures that we hold dear were just thrown aside." He is disappointed that the US has not had a broad-ranging Chilcot-style investigation into the decision to invade Iraq.
The villain of the film is Lewis "Scooter" Libby, Cheney's chief of staff. Libby was convicted of perjury and obstruction of justice over the investigation into the leak of Plame's identity. His 30-month prison sentence was commuted by Bush, but his career in public service was over and he was barred from practising as a lawyer, though he is still active as a lobbyist. Wilson says it "meant quite a bit" that Libby was found guilty, because it "demonstrated that there is justice in the justice system".
Wilson, 61, has returned to running the international business consultancy he established when he retired from diplomatic service but which became virtually moribund after 2003 as work dried up in the wake of the administration's attacks on him. Plame, 47, is co-writing a spy novel, doing consultancy work for a scientific research institute, and campaigning against nuclear weapons. Not going back to work was, he says, never an option. "Contrary to what you may believe – or maybe we're just not very good at this – books and movies don't actually make people a lot of money. They may make some people a lot of money, but not everybody. We still work for a living."
Fair Game draws a line in the sand for the couple. But Wilson accepts that it is this battle that will define his life. "I suspect that win, lose or draw, this will be how I'm remembered, unless I win the Nobel prize for physics, which is not likely because I'm not a physicist."
• This article was amended on 7 March 2011. The original said that Saddam Hussein had been trying to buy enriched uranium from Niger. This has been corrected.
