The alarming news flashed across America's TV screens on Thursday evening: government agents had thwarted an al-Qa'ida plot, using home-grown American terrorists, to blow up the Sears Tower in Chicago in a ghastly repeat of 9/11.
When the dust had settled barely 24 hours later, a rather more modest version of events had emerged. The seven young black men arrested at a warehouse in Miami and Atlanta had never been in touch with al-Qa'ida, and had no explosives. Their "plan" to destroy America's tallest building was little more than wishful thinking, expressed by one of them to an FBI informant purporting to be a member of Osama bin Laden's terrorist organisation.
Even the FBI admitted as much. John Pistole, the bureau's deputy director, described the plan on Friday as "aspirational rather than operational" and admitted that none of the seven (five US citizens and two Haitian immigrants) had ever featured on a terrorist watch list.
In essence, the entire case rests upon conversations between Narseal Baptiste, the apparent ringleader of the group, with the informant, who was posing as a member of al-Qa'ida but in fact belonged to the South Florida Terrorist Task Force.
At a meeting "on or about 16 December" according to the indictment made public as the men made their first court appearance in Miami, Mr Baptiste asked his contact to supply equipment including uniforms, machine guns, explosives, cars and $50,000 in cash for an "Islamic Army" that would carry out a mission "just as good or greater than 9/11".
In fact, the conspiracy seems to have extended little further than those words. By last month, it had all but fizzled out, amid squabbling among Mr Baptiste's followers. Even their religious leanings are in dispute. Neighbours say they were part of a group, called Seas of David, that mixes Christian and Islamic elements.
That did not deter the US Attorney General, Alberto Gonzales, from summoning a press conference in which he denounced an attempt to "wage war against America". But the threat, even he admitted, was not immediate - and those who posed it were in fact merely a few semi-unemployed men, most of them petty criminals, from Liberty City, a poor black neighbourhood close to the centre of Miami.
If the case has any significance in America's "war on terror", it is not as a present danger, but as a harbinger of possible future risks. Despite countless scare stories in the media, colour-coded alerts from the Department of Homeland Security and grim official warnings of al-Qa'ida sleeper cells in the country waiting to do their worst, the US has not suffered a single terrorist attack since 9/11.
Nor have the authorities unearthed much of a terror threat. The Justice Department claims that 401 people have been charged with "terrorism-related offences" since the 2001 attacks, and that 212 have been convicted. In fact only a tiny number of these were true terrorists.
The tendency - duly followed last week by Mr Gonzales - has been to hype. The precedent was famously set by his predecessor, John Ashcroft, who called a press conference during a visit to Moscow in 2002 to announce the arrest of Jose Padilla, the so-called "dirty bomber" said to be preparing an attack on Washington with a radioactive device.
Mr Padilla languished incommunicado in a navy brig without charge for over three years. He has been transferred to a civilian prison, and faces trial in Miami later this year on different, much vaguer, terrorist charges. An alleged sleeper cell was unearthed in Detroit, but those convictions were quashed in 2004 when it emerged that prosecutors had manipulated evidence. In December 2005, the trial of Sami al-Arian, accused of links with Islamic Jihad terrorists, ended in embarrassment for the government when the Florida university professor was acquitted.
The biggest successes have had little to do with US law enforcement. Richard Reid, who tried to blow up an American Airlines plane with a shoe bomb in December 2001, was stopped by alert flight attendants, while Ahmed Omar Abu Ali, the Virginia student serving a 30-year sentence for threatening to kill President George Bush, was caught by police in Saudi Arabia.
But US experts say last week's dismantling of the Miami plot could be a pointer to things to come, when home-grown terrorists, not foreign-born Islamic radicals, pose the threat. The July 2005 attacks in London in particular are frequently cited as a model for what might happen here, when disgruntled young citizens turn against their own country. The arrest in Canada this month of 17 people allegedly planning major attacks against targets in Ontario also came as a shock south of the border.
Patrick Abraham aka 'Brother Pat', arrested along with:
Burson Augustin known as 'Brother B'
Rothschild Augustine or 'Brother Rot'
Narseal Batiste alleged ringleader, aka Prince Manna
Lyglenson Lemorin or Brother Levi
Naudimar Herrera aka Brother Naudy
Stanley Grant Phanor or Brother Sunni