‘I’m afraid not,’ Karen says quickly. ‘At least, not today, but some other time would be great,’ she adds.

Next, they stop outside a big brick building. Large sections of its exterior are stained black by the coal soot that seems to cover everything on the island like a film. Up here, it looks as though any attempts to remove it have long since been given up. When they enter through the big double doors, Karen lets out an involuntarily gasp. Looking down the long, narrow aisle, flanked on either side by oak barrels all the way to the ceiling, makes her feel suddenly dizzy. For a brief moment she’s convinced the racks are about to collapse and bury them under tonnes of whiskey-scented oakwood, but she has no time to indulge that thought. Tryste finally seems to have abandoned his role as their guide and is hurrying further into the warehouse. The air is damp and raw and they pass countless perpendicular aisles, each flanked by floor-to-ceiling racks holding large oak barrels full of maturing whiskey. Eventually, Tryste stops outside a closed door and Karen realises with some surprise they haven’t run into a single one of the distillery’s employees.

‘Most people are on leave until after New Year’s,’ Tryste says as though he could hear her unspoken question. ‘But Jens is supposed to be here.’ He taps a quick tattoo on the door and opens it without waiting for a reply.

‘Hi, there, Jens,’ he says. ‘The police are here to ask some questions. Is it OK if I abscond now?’ he adds, addressing Karen. ‘The wife wouldn’t be best pleased if I was late coming home again . . .’

‘Absolutely. We’ll be in touch if there’s anything else.’

Behind a large L-shaped desk sits a blond man with glasses pushed up to his forehead. His unkempt hair is standing straight up, as though he has been frantically running his hands through it. He gets up and extends his hand with a friendly, slightly quizzical smile. Even though the room is cool, there are dark pit stains on his grey T-shirt. His stocky build hints at an impending transformation from what might still pass for a thickset young man into a fat old codger.

‘Jens Groth,’ he says. ‘You’re welcome, of course, though I’m not sure how I can help.’

Jens Groth may be one of the distillery’s owners, but his office is considerably less grand than William Tryste’s, Karen notes while she and Byle sit down on chairs in front of the desk, which is almost hidden under countless stacks of paper. Jens Groth carefully pushes two of the stacks aside, as though to create a corridor for communication with his visitors.

‘There’s a lot of paperwork in this business,’ he says with a weary smile. ‘So, what can I do for you?’