Like all great Washington scandals, there is something bafflingly petty about the original crime that sent Justice Department mole-hunters thundering into the White House.
Like all great Washington scandals, there is something bafflingly petty about the original crime that sent Justice Department mole-hunters thundering into the White House. But this probe is truly dangerous for the Bush administration - the first real whiff of an abuse of power in a White House that has so far avoided major scandal.
The basic allegation is simple: in July, someone in the White House leaked the name of an undercover CIA operative, specialising in banned weapons, to a few favoured journalists.
On one level, the leak was no more than an act of spite aimed at the agent's husband: a former US ambassador who had gone public with charges that the White House knew there was no truth to the claim that Saddam Hussain had sought uranium from Niger. He claimed the administration nonetheless used the story to buttress its case for war.
The crisis now facing the White House is equally simple. Thanks to an obscure 1982 law, leaking the name of an undercover CIA agent is illegal, carrying a maximum penalty of 10 years in prison.
Even if no one goes to prison, there is a good prospect that someone will have to resign. The ambassador in question, Joseph Wilson, has accused Karl Rove, the top political operative in the White House, of "at a minimum" condoning the leak.
Wilson says he has first-hand reports that Rove called senior journalists after the initial leak to draw their attention to his wife's occupation. Rove allegedly called Wilson "fair game". In Seattle last month, Wilson said: "It is of keen interest to me to see whether or not we can get Karl Rove marched out of the White House in handcuffs."
There is no suggestion that US President George W. Bush knew about the leak, and there is no sense that his position is in danger. But it looks bad for him. A super-patriotic administration whose proudest boast is its relentless war on global terror, stands accused of blowing the cover of a key undercover warrior for political reasons, risking her life, and the lives of every contact she ever cultivated.
Among Bush critics, Karl Rove occupies a similar position to that held by Alastair Campbell in Downing Street in British politics, only more so: a ruthless Svengali with astonishing power over his supposed master.
Outsiders might expect that the administration's flag-waving hawks would love the CIA. In fact, red-blooded conservatives regard the CIA as a pale shadow of its Cold War self. To them, it is an over-cautious bureaucracy staffed with pen-pushers who would rather hold conference calls with shifty foreign intelligence "allies" than get down in the souks of the Middle East.
In particular, the CIA was out of favour for failing to provide the hawks with a cast-iron case linking Saddam to banned weapons and Al Qaida. By summer, as the intelligence case for Iraq came under scrutiny, the leaks and counter-leaks were flying as hawks and CIA tried to cover their backs. If the White House was calling journalists to say that an enemy's wife was a CIA agent, the subtext would have been clear. Wilson was "one of them", a CIA appeaser opposed to the war.
If the leak was first published in July, why has it taken so long for this scandal to blow up? The truth is the story would have little impact as long as the only ones complaining about the leak were Joe Wilson and a few liberal journalists.
All that changed at the weekend when a "senior administration official" attacked his colleagues for the Wilson leak. It was "meant purely and simply for revenge", the official told The Washington Post, and was "wrong and a huge miscalculation".
The betting was that that unnamed official was not a million miles from the CIA director, George Tenet - the man who demanded the Justice Department investigation. This now looks like an inter-agency fight and the CIA is a bad enemy to pick. The agency bears grudges and looks after its own. This scandal has some way to go.