No one makes thrillers quite like the English, with their ability to conjure out of the most mundane situations and artefacts the heights of creepiness and menace - exactly the cleverness of Sunday's two-parter Bon Voyage.
With echoes of the Madeleine McCann affair, this is the story of an English family on a camping trip to France, expecting the typical, rather boring, bickery sort of fortnight the Poms usually have abroad, when the two children are kidnapped.
Who knows what actress Fay Ripley has done to offend the writers and producers of Britain, but the former Cold Feet star is yet again cast as the blandly evil villain of the piece.
No more Mrs Nice Guy roles for her. But as with her former Cold Feet alumnus James Nesbitt in Jekyll, she does such a terrific sociopath act that her typecasting of late is forgivable.
Ripley plays Linda, the mumsy half of a boring couple our family meet on night one of their trip, as they set up camp.
Mr Bore is Simon (Daniel Ryan), pleasant and helpful - "I'd put the tent pegs a little farther apart if I were you" - and Mrs Bore, Linda, a little more aloof, but all smiles.
This is exactly the sort of jolly, middle-aged couple that our family, Neil (Ben Miles) and Liz (Rachael Blake), most dread being dogged by on holiday. Neil and Liz are 30-something and sexy, while Simon and Linda, in their all-mod- cons campervan, seem pretty stodgy.
Still, it seems rude not to accept their invitation to an evening drink inside the campervan. Here, boring yields to slightly odd.
Linda shows a barely repressed febrile interest in children, lamenting Neil and Liz's liberal attitude toward their children.
Linda and Simon's two are already tucked up in bed, apparently, while David, 10-ish, and Sarah, 16, are out with newfound friends.
Meanwhile Simon shows a sneakingly chippy interest in Neil's car - a pale blue vintage BMW - and evidently large income. But this all seems only the sort of nosy, judgmental behaviour typical of many staid middle-aged folk.
Still, the inklings of unease mount. Simon has an unsettling conversation with teenaged Sarah, suggesting he has some sort of unwholesome interest in her.
Next morning, Neil's car has been keyed. Liz is by now determined to avoid further contact with this tiresome couple, so the family move on to a new campsite. On the road, they are pursued by the campervan, which nearly runs them off the road.
In the resultant altercation at the roadside, Simon insists he was only being playful. Linda, her smiling passive-aggression now quite blood-curdling, tells Liz, "Boys will be boys, eh?"
By now, your inklings have well and truly inkled. You know the family have to get as far away from Simon and Linda as the BMW will carry them.
Except that it gets a flat tyre - apparently courtesy of a little feint we noticed by Linda at the roadside earlier, inserting a tent peg.
They get the car going again, but by now they are seeing campervans everywhere, thinking Simon and Linda have tracked them down again.
A few red herrings later, they're stopped by the police, who are searching for a missing boy, Toby, who was playing cricket with Linda at the first campsite.
Not yet connecting Toby's disappearance with creepy Simon and Linda, our family give a statement to the police and get back on the road.
At this stage, you have reached the classic "Stay in the car, keep going and don't look back" mode. But of course, the family do get out. Because on a darkened road, Toby runs out in front of the car, and they hit him, killing him.
Let's pause here and admit, this is a bum note in an otherwise sound story.
This is the most massive and incredible coincidence. Unless Toby's evil abductors had lain in wait for the blue BMW and physically hurled the boy in front of it, the odds of his being hit by their car are positively Lotto-esque.
But the story demands it be them because, of course, hidden in the bushes nearby is the campervan – Simon and Linda's portable lair. There's no sign of the evil couple but it's clear they had abducted the boy.
While Neil and Liz connect the dots, rushing about in the bush and wondering what to do about the dead child - did I mention it is also by now a dark and stormy night? - their children wait anxiously in the car. And when Neil and Liz get back to the car, naturally the children are gone, and lo, there's the campervan driving away.
The trailer for next Sunday makes it clear that Simon and Linda, having lost their own children some years ago, have confiscated and imprisoned David and Sarah, and probably other children in the past, hoping to "train" them into being replacements.
Naturally, the police suspect Neil and Liz of all sorts - their story is so preposterous and the only material evidence is a dead child.
For all its plot flaws, Bon Voyage will be worth staying up for next Sunday because of the psychological terror it has built up so well. Simon and Linda's pathology is fascinating: they have come to feel entitled to replace their lost children, and to judge the perceived shortcomings of other parents.
Conversely, Neil and Liz are forced to agonise over the quality of their own parenting, to have it publicly and officially questioned, when they have done nothing wrong.
The trailer also promises more of the terror of the mundane. The stolen children's battles with their mad captors take place over that most commonplace of articles, the tea table.
Charitably, TV One probably put this programme on really late, guaranteeing it a small audience, in deference to the manufacturers and retailers of campervans.
You'll never want to get in one again.
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