WHATEVER happened to the mythical American neighbourhood, that Rockwellian idyll of friendliness and normality, where no problem could not be resolved by the community spirit and nothing nasty ever happened?
The scarcely believable tale of the three girls kidnapped and held for a decade in a house on an ordinary street in Cleveland, Ohio raises many questions.
It's hard to imagine that they didn't have chances to escape the clutches of their single jailer Ariel Castro and end their ordeal sooner.
Did some form of Stockholm-syndrome bonding develop between Castro and his victims, Amanda Berry, Gina DeJesus and Michelle Knight?
Nor do the Cleveland police emerge with much glory from the affair, having apparently failed to react even to reports of a naked woman on all fours and in a dog collar in Castro's back garden.
But the biggest mystery is the neighbours. How on earth did they see nothing amiss for so long?
Here, in America, such things are not supposed to happen. In the inner cities, maybe, but not in the suburbs, where streets hold annual block parties and local kids sell lemonade on the corner.
All of the above are facets of the US neighbourhood community which, when written about, almost automatically comes with the adjective "tight-knit".
This is, moreover, the land that invented Neighbourhood Watch, the system of local security that can on occasion in the US verge on downright vigilantism.
Move to America and the sense of neighbourhood is far more palpable than in many other countries, at least in my experience.
Here, in Washington, you feel you know everyone. That comforting, reassuring term 'community' permeates American society. Send your child to the local school and you are part of that community.
You can be part of the disabled community, the gay community, or any particular interest community.
Often, they have strict rules. If you live in some gated community, woe betide you if you paint your house the wrong colour or fail to mow your lawn.
And the pattern extends to the political system, which is dominated by special-interest groups of every hue. From healthcare to banking reform to gun control, every piece of major legislation that comes before Congress is a battle between lobbies and interest groups – in other words, 'communities'.
The National Rifle Association may be a fearsome organisation. Less so, perhaps, when you think of it as the 'gun-owning community'.
I've always wondered whether this habit can be traced in part to the German input into the collective American psyche. It is often overlooked that Germans – not Italians, Irish or English – are the largest ancestry group in the US.
I lived in Germany for three years in the 1980s and an abiding memory is of the nosiness of neighbours, well-meaning but based on the belief that a person must behave according to local community norms. However, I digress.
Cleveland has somehow given the lie to all this. If communities are supposed to look after their own, this particular one failed.
Of course, not everywhere is the same. I live in white and prosperous north-west Washington DC. Castro lived on the poorer west side of Cleveland, in a neighbourhood where many people were of Puerto Rican origin. Even so, maybe if they had done what they were supposed to do – and had the police followed up more thoroughly – Castro's crime would have been exposed far sooner.
Moreover, so awful was that crime that no one could have imagined it. When you move into a new neighbourhood, you tend to assume the people next door are okay. When you see them digging in their garden, you don't think of serial killers disposing of their victims.
Yes, 100-odd children are kidnapped in the US in the average year. But even when a house is locked and you can't see in, you don't suspect that three of those children are inside, prisoners being abused, even tortured.
Perhaps we expect too much of the American neighbourhood. Even in the closest-knit community, not everything is shared.
The story from Cleveland – horrible, incomprehensible, redeemed only by its happy ending – is proof that no human being, least of all the person over the garden fence, is ever completely knowable.