"But the dog did nothing in the night," replies his interlocutor.
"That was the curious incident," says Holmes.
The dogs aren't barking over the US-Iraq treaty, either, and that is equally curious. To begin with, the Iraqi dogs aren't barking.
Prime Minister Nouri al-Maliki clearly doesn't like the deal that the Bush administration is forcing on him, but will accept it because his Government wouldn't survive a week without US military support.
The Shia religious authorities will not issue a fatwa against it, because their first priority is to preserve the Shias' newfound domination of Iraq.
But in fact most Iraqis who know about it hate it.
That includes most of the Iraqi Parliament's 270 members, who sent a letter to the US Congress last week asking it to reject any US-Iraq security agreement unless the White House agrees to a specific timetable for withdrawing American troops from Iraq.
But Congress will not get to vote on the deal, because the White House has defined it not as a treaty (which has to be ratified by the Senate) but as an alliance (which doesn't).
Equally curious is the lack of outcry in the US media.
Last week, the Middle Eastern correspondent of The Independent, Patrick Cockburn, published two leaked reports about the terms of the "alliance" and the tactics that the Bush administration is using to get the Iraqi Government's approval by the end of July.
Nobody denied them, but hardly any mainstream outlet in the US media reported them as a major story, either.
It's not necessarily a conspiracy. The exhausting Democratic primary campaign finally came to an end last week, and it's very hard for the media to focus on two stories at once.
Besides, the market leaders who define what is "news" know that the US public is sick of hearing about Iraq, and they are sick of it themselves.
But it's still remarkable that the details of the deal by which the US gets permanent bases in Iraq, and the threats that are being made to extort Iraqi agreement, are getting so little coverage.
Mr Cockburn revealed that the United States will retain more than 50 military bases in Iraq as part of the "strategic alliance" it is pressuring Baghdad to sign.
They will not be defined as US bases, however, since US negotiators insist that a perimeter fence with a few Iraqi soldiers on it is a sufficient fig-leaf to make it an "Iraqi base".
However, those American soldiers on "Iraqi bases" will be able to carry out arrests of Iraqi citizens without prior consultation with the Iraqi authorities, if US negotiators get their way.
US soldiers, and American civilian contractors as well, will enjoy full legal immunity for their actions.
So it will remain the case, as it has been since the invasion, that any American employed by the US Government in Iraq can kill any Iraqi without having to explain and justify his or her actions to Iraqis.
Indeed, the United States will be entitled to conduct entire military campaigns on Iraqi soil without consulting the Iraqi Government.
The US Government is not even willing to tell the Iraqi Government what American forces are entering or leaving Iraq under the terms of the "alliance", apparently because it fears that the Government would inform the Iranians.
Terms of this sort are familiar from the era of the European empires, when similar treaties were signed between, for example, the British Government and its Iraqi colony in the Middle East.
Ali Allawi, minister of finance in the Iraqi transitional government 2005-06, warns that this is "a reprise of that treaty", and predicts that it will lead to the same "riots, civil disturbances, uprisings and coup" that filled the quarter-century between the British-Iraqi treaty in 1930 and the Iraqi revolt that finally overthrew the local puppet regime in 1958.
Some sort of treaty is needed to provide a legal basis for a continuing US military presence in Iraq, since the existing UN mandate lapses at the end of 2008.
The particular treaty that the White House is forcing on Baghdad is designed to justify a permanent military occupation of Iraq, and as far as possible to tie the next administration's hands when it comes to pulling US troops out of the country.
The Iraqi Government will probably accept the US demands after some protests, because its survival depends on American troops.
Washington is also threatening to allow $20 billion of outstanding US court judgements against Saddam Hussein's regime to be executed, wiping out 40% of Iraq's foreign exchange reserves, if the Government in Baghdad does not co-operate on the treaty.
The trickier question is what happens if President Bush's successor is not the like-minded John McCain?
To the extent that they can successfully pretend that the US has won the war in Iraq, they can attach a very high political cost to Barack Obama's pledge to pull US troops out of the country, and this treaty also serves as part of that charade.
But it does not oblige US troops to stay in Iraq forever. It just says they can if they want to.
This game is not over, and neither is the war.
Gwynne Dyer is a London-based independent journalist.
