Some years ago, during an interview for basic training as an undercover operative for the Central Intelligence Agency, Valerie Plame was asked an unexpected question: What would you do if you were conducting a debriefing alone with a foreign agent in a hotel room when there was a knock at the door and you heard someone shout, “Police!”? Quick as a flash, the young Miss Plame responded: she would strip off her blouse and leap into bed with her accomplice, she said, thereby providing an immediate and wholly plausible alibi, and saving the agent and herself from certain discovery.

It was this sort of quick thinking that marked Plame out as a young woman with a promising future in the CIA. And it is an image I am struggling to get out of my head as I sit in a hotel room in New York with her this week – and someone knocks at the door. The mind races but, needless to say, the flesh remains static: I’m not a foreign agent; it’s not the police, only the bellboy; and Plame is no longer a spy.

Indeed, Valerie Plame is probably the most familiar, most talked-about, most glamorous ex-spy in the world. In the past few years she has shot to improbable stardom as a kind of icon for all those who are anti-Bush. It was her name that was famously leaked to the press by Bush Administration officials four years ago in what soon became a full-blown Washington scandal that kindled in the President’s critics brief dreams of another Watergate.

Plame, with her Hollywood-blonde bangs, her disarming smile and touchy-feely charm, probably epitomises the odd transformation that the CIA has undergone in the past few years.

There was a time when, to those who feared and loathed America, the agency was the greatest object of their animus. When it wasn’t toppling democratically elected regimes in South America, it was infiltrating student movements and trade unions in Europe or putting exploding cigars in Fidel Castro’s beard. It was the black heart of American foreign policy and it loved practising its black arts wherever it could.

But something strange happened. In the past ten years, and especially over the issue of the handling of intelligence that led to the Iraq War, the CIA became the good guys in this narrative. They were the honest stiffs, trying to inject some truth and accuracy in the headlong rush to war. It was the CIA that was most doubtful about the case for war. While the Pentagon and the White House, especially Vice-President Cheney’s office – ably assisted by Tony Blair, supposedly – twisted the intelligence, the CIA harboured grave doubts. The organisation once seen as a rogue agency conducting its own foreign policy from Santiago to Sydney was now the last repository of truth and honesty, manipulated by unscrupulous politicians.

That, at least, is the version of history according to Plame and others. In 2003, after several years in clandestine posts in the US and overseas, she found herself head of a counter-proliferation group that was investigating Iraq’s weapons of mass destruction programmes under Saddam Hussein.

That summer, her name was leaked to a newspaper columnist after her husband had written an article attacking a key piece of evidence that the Bush Administration had used to justify the war.

Joseph Wilson wrote how he had, a year earlier, been sent to investigate claims – backed by British intelligence – that Iraq had been trying to acquire uranium for nuclear weapons from Niger in Africa. After a brief tour and meetings with some old contacts (he had been an ambassador in Africa) he reported back to the CIA that he had found no evidence of the Iraqi programme. He attacked the Bush Administration for continuing to insist – after he had supposedly proved otherwise – that Iraq was still seeking the uranium in Africa.

The Bush team, not surprisingly, pushed back. They cast doubt on Wilson’s credentials, said his visit had not been all that conclusive in any case and, fatefully, said he was no real expert on any of this stuff but had been sent on the trip only because his wife worked on counter-proliferation policy at the CIA. It was all a cozy piece of nepotism, they suggested.

Now, as it happens, much of this is accurate. The problem, though, was that Ms Plame, his wife, was an undercover CIA official – and unauthorised publication of the identity of an undercover agent is a crime punishable by many years in prison.

So began Plamegate. A special prosecutor was appointed to investigate the leak amid fevered speculation that Karl Rove, President Bush’s mastermind and alter ego, and Scooter Libby, Cheney’s chief of staff, were behind it and were heading for the slammer.

In the event, after an investigation that lasted three years and included the bizarre spectacle of a prosecutor sending a reporter to jail for not revealing her sources – egged on by the editors of her own newspaper – Libby was found guilty by a jury of obstruction of justice and perjury. He was later pardoned by President Bush. No charges were ever brought against Rove. Now the woman at the centre of the storm is speaking out.

The title Fair Game is a mocking reference to a remark said to have been made by Rove to a TV reporter, when the White House was busy trying to rebut Wilson’s contentions. “Wilson’s wife is fair game,” he said.

Part of her game is evidently to show how unreasonable her opponents are. She is greatly helped in this by the silly decision by her former bosses at the agency to insist on blocking out large pieces of the book’s text – redactions, as they are known in American legal parlance – on the ground that they might compromise national security.

The effect can be comical at times. An entire chapter on her early life as a spy in a (redacted) European country is entitled “(Redacted) Tour” and all references to that country have been similarly blacked out – even though a quick Google search from other sources, and obvious readable references in the chapter will tell you that it was almost certainly Greece. Chapter 3’s entire title, and most of its contents, are redacted. And we’ll never get to know how she made the acquaintance of her husband, because all that is classified too.

Plame thinks this is not the result of pettifogging bureaucracy but a sinister and continuing attempt by the administration to destroy her.

“This is continued political payback, and in a sense, further demeaning to me and demeaning of my role and responsibilities. Because if you diminish me then you diminish the crime.” Some of her observations will disappoint those who believe the whole war was funded on a deliberate fiction about Iraq’s WMD. As a senior intelligence official, in fact, she was quite happy to endorse the Administration’s general view of Saddam Hussein. “There was no doubt he was a man of evil intent and certainly he used WMD on his own people – you can’t give him the benefit of the doubt – and certainly not in the aftermath of 9/11.” She adds, however, that it was only when Colin Powell, then Secretary of State, made his famous argument to the UN Security Council in February 2003 that she became truly uncomfortable with the march to war.

But she doesn’t stint in her accusations against Bush and his aides about their motives and behaviour in leaking her identity after the Niger kerfuffle.

“My cover was secure and the last possibility we anticipated was that they would commit treason,” she says, almost casually dropping the T word into the conversation.

Steady on, I say. Treason, punishable by death, surely means a wilful effort to hand the country over to its enemies. Wasn’t Plamegate just a rather nasty political squabble, elevated to a scandal by the indefensible, but surely inadvertent, outing of her role as a spy by people who ought to have thought a little bit before they spoke? “Treason,” she insists.

No one would seriously argue that the leaking of a covert agent’s name is deeply damaging to national security, as Plame explains.

“By outing someone’s covert identity”, she tells me, “it puts in jeopardy all these assets we have promised we would keep secret – not to mention any future sources who may have information of critical intelligence”.

But she never manages to shake off the impression that she was by far and away the most effective publicity-seeker herself. It was, after all, she who first put a face to the name that had been outed, when she happily appeared in a front cover story in Vanity Fair, looking every bit the Hollywood maven, complete with Grace Kelly-type headscarf, cast as the femme fatale in one of the greatest spy scandals of all time.

“It’s been more trouble than it’s worth,” she acknowledges, but adds, “if that’s the worst thing that can be said about me, I can live with that.” Plame tries valiantly to make the case that her extraordinary moment in the glare of public attention was an event of epoch-making significance in American political history. Plamegate was supposed to have been the ultimate scorching revelation into the inner crookedness of the evil Bush empire. It was to have blown the gaffe on the manipulation of intelligence in the run-up to the Iraq War. It was, in the wilder imaginings of the Administration’s critics, proof that the war was illegal and criminal.

But what did it actually amount to? A Senate committee (including Democrats) investigating the conclusions of Plame’s husband about his famous trip to Niger found them unconvincing. The British Government to this day stands by the claim that Saddam Hussein was seeking uranium in Africa. Despite all this, the Bush Administration did actually officially retract – long before the scandal really exploded – the claim that Iraq had been seeking nuclear materials in Niger, and it had never been a central part of the intelligence case for war in any case.

The man who actually did first reveal Ms Plame’s identity to the press was not in fact Libby but Richard Armitage, the Deputy Secretary of State at the time. And he was never prosecuted for it because the special investigator was never convinced that it was a prosecutable crime in any case. The burden of proof in such a case is very high, and requires the perpetrator to have acted with malicious intent. The man who was prosecuted, Libby, was convicted, not of the underlying crime (there wasn’t one) but, in the classic Washington manner, caught in a perjury trap by a zealous prosecutor.

It was all, despite the grandiose claims, simply another theatrical and expensive remake of the classic Washington scandal. In Washington the pattern these days is to criminalise every political difference. In an often deadlocked political system, the best way to make progress is by asserting some breach of the criminal law.

Everybody claims that the system has been demeaned and defiled, that the very essence of American democracy is under threat. Then we discover nothing very much. So everybody gets to write a book and if they’re really lucky, a contract for the film rights.

And just as it has always been in Washington, in a curious way, everybody wins.

Explore Books

• Book Extracts

• Book Reviews

• Books Group

• Audio Books

Times Recommends

• The Sunday Times 100 best holiday reads
• What will we be reading this summer: the booksellers predict
• Literary festivals: a survivor’s guide