They padded naked through the adjoining doorway that, unbeknown to the building’s owners, their father had installed between the two lock-ups – both units were registered to different, non-existent people, so if anyone ever discovered this by accident, it wouldn’t matter greatly – and took a shower, thoroughly soaping themselves and shampooing their hair. After this, they blew dry, put on jewellery and makeup and got dressed again, now in slinky, clingy tops, miniskirts and tall, strappy shoes.

If they got stopped for any reason on the way home now – which was unlikely because the car they kept in the second lock-up was a respectable silver-coloured Volvo V90 estate, fully documented and in mint condition – they were nothing but a pair of ditzy party-girls returning from a cracking night out. And no, officer, they didn’t mind providing specimens of breath for breath-tests, because they never drank and drove; their strict, law-abiding father wouldn’t hear of it. If anyone queried the marks on Alyssa’s face, meanwhile, it would be a tale of woe about a violent ex-boyfriend who now, thankfully, was history.

They returned to Cotely Barn shortly after 2.15am, parking on the drive alongside their father’s Merc. The address was 27, Cedar Lane, and it was the essence of suburban respectability, the house once an ivy-covered four-bed detached, surrounded by lawns and flowerbeds, though their father had extended it several years ago, constructing a fifth bedroom above the formerly free-standing garage, which had also now been connected to the main house. The value of the property had increased dramatically, but the real advantage lay in the fact that prisoners could now be brought indoors, in the Volvo’s boot, without anyone noticing, and taken away again in the same manner.

The girls let themselves in by the front door, tittering and giggling, again as if they’d just had a great night – normality was so important – and entered a wood-panelled downstairs area, neatly carpeted and tastefully furnished, dotted with original paintings and other ornaments, and now lying in midweek darkness.

To the average outsider, the master of this pleasant-looking house led an entirely conventional, inoffensive life, coming and going unobtrusively, pruning his roses at the weekend and attending neighbourhood barbecues. If his neighbours ever enquired, and they often did because he was affable and approachable, he’d tell them that he ran a bunch of small businesses but that he was now thinking about retiring – all of which was true. He would be vague if the nature of his main expertise came up, talking in airy terms about ‘trouble-shooting’ and ‘consultation’, though again this was at least partly true. He spoke rarely about his wife, who most people assumed must have died rather than left, because he had a pair of college-age twin daughters who were beautiful, intelligent and chatty, and seemed very content with their lot.