‘Rubbing alcohol,’ said Cooper. ‘It’s an antiseptic and cleaner.’

‘And in everyone’s first-aid box,’ said Fry cheerfully. ‘Even farmers who cut themselves use it, I bet.’

‘Unless they drink the stuff,’ said Murfin.

‘Really?’

‘Well, just something I’ve heard.’

Fry shook her head, but didn’t seem downhearted. ‘And finally … something called pseudoephedrine.’ She stumbled over the last word and tried again, shifting the emphasis on the syllables. ‘Pseudoephedrine.’

‘What the heck is that?’

‘It says here it’s the active ingredient in proprietary decongestants, such as Sudafed. But there seems to be an awful lot of it.’

‘Someone had sinus problems at Pity Wood,’ suggested Murfin. ‘I’m not surprised. I reckon you’d be permanently bunged up with a cold, if you lived there. I was sneezing myself when I was up at the farm yesterday.’

Fry stared at him for a moment, as if horrified at the idea of Murfin with a head cold. Cooper could practically see her mind working, pieces falling into place in that efficient, clockwork way her brain had. There were no leaps of intuition with Fry, just the logical adding of one item of information with another, to come up with a final answer, already checked and validated.

At that moment, DI Hitchens entered the CID room with an envelope in his hand. He handed it to Fry with a slightly sheepish look.

‘Diane, here are your tickets for Dublin. I hope you’ve got your passport.’ Fry put the chemist’s report down. ‘I’m ready, sir.’

‘Good. Your flight leaves at one twenty-five.’

They’d booked her on a cheap Ryanair flight, of course. The fare to Dublin was less than it would have cost her to catch a bus to Sheffield and back. Robin Hood Airport, too – which meant she had to drive right over to Doncaster to catch her flight.

Fry checked in, went through security, and decided to have a drink at the airside bar. And then she had to sit and wait. An hour’s flight to Dublin, and an hour twiddling her thumbs. She watched her fellow passengers waiting patiently near the gate for boarding. Most of them seemed to have books or magazines, mindless stuff to while away the time. If only she could sit still and turn her brain off for an hour, the way these people were able to do.

When she’d finished her drink, Fry began to prowl the departure lounge, feeling restless and uneasy. She noted that ThomsonFly operated flights to Prague from this airport. That would have been handy for Nadezda Halak, she supposed, the Czech Republic being right next door to Slovakia. In fact, they used to be one country, didn’t they, before parts of Eastern Europe began to break up? But had Czechoslovakia separated before, or after, Nadezda arrived in the UK?