While she was still sitting there, trying to get lost in inconsequential thoughts as a defence against the scary ones, the end of the cloud bank unrolled with slow theatricality from the face of the moon. In its sudden spotlight, Kennedy saw something move on the roof of the building opposite. It was only for a second. Probably a cat, or nothing at all, a piece of garbage light enough to be lifted on the wind. Except that it was moving against the wind.
As casually as she could manage, Kennedy took another sip of her drink, set the glass aside and ambled away from the window, out of the door of the room into the hallway that ran the length of Izzy’s flat. As soon as she was through the door and out of any possible line of sight from the roof, she sprinted down the hallway, took the stairs three at a time and got to the street door inside of twenty seconds.
Then she slowed and walked out onto the street at a casual pace, her head down, trusting to the darkness to cover her. She strolled away down the street, turned the corner, quickly crossed the road and took an alley that led behind the buildings on the opposite side.
The building directly facing Izzy’s was another residential block. Kennedy was in luck: a teenaged boy and girl walked out of the back door as she approached it, and the girl obligingly held it open for her.
She found the stairs and climbed them, quickly but quietly. At the very top, there was an emergency door that led out onto the roof. Conveniently close to hand, a fire extinguisher sat in a niche on the wall. It was of the black CO type, small enough and solid enough to make a reasonably good weapon. Kennedy snatched it up and slammed the door open.
And found she was facing the wrong way. The door opened towards the rear of the building, not its front. In the echo of the door’s slamming, there were some other sounds — a scrape of stone or gravel, and then a rustling insinuation that died away quickly.
She ran out onto the roof and around the low housing in which the fire door was set. There was nothing else obstructing her view and no sign of anyone or anything that shouldn’t be there.
Still wired, still suspicious, she patrolled the length of the roof, looking across directly at the windows of Izzy’s flat. She could see where she’d been sitting, her empty glass still on the sill, and she tried to work out from that where the movement would have been.
She found it, in the end. The surface of the roof was gravel laid on green mineral felt and a small area of it bore both the scuff of footprints and the indentations of someone sitting or kneeling there for a long time.
Not paranoia. She was being watched.
And it seemed like the watcher must have wings, because there was no other way off the roof that she could see.
9
Partridge was waiting outside Ryegate House’s main entrance when Kennedy arrived the next morning, with the smallest dog-end she had ever seen wedged between his index and forefinger. He had two companions, both standing nervously upwind of Partridge’s cigarette: a shy, slightly fey-looking young man and a serious, bespectacled woman, both in their early twenties and dressed in what looked like their Sunday best. Partridge himself wore a shabby donkey jacket over a plain white T-shirt and dark-blue trousers with more pockets than anyone could actually need. He took Kennedy’s hand and greeted her with old-world civility.
Then he introduced the other two: ‘Kathleen Sturdy and William Price, of the University of Swansea’s School of Engineering.’ They were standing to either side of a solid-looking steel box with rows of handles bolted to its sides and foam-rubber chocks affixed to each corner.
‘This is the Kelvin probe?’ Kennedy asked.
‘This is just the scanning head,’ Partridge said. ‘There are a lot more components. They’re parked in a van three streets away — closest we could get. My God, I hate this city.’
‘That just makes you a bigger hero, John.’ Kennedy turned to the young man and woman. ‘And I assume you two are the operators. Thanks so much for taking the time to do this.’
‘Actually, we’re graduate students,’ the woman — Kathleen — answered. Her voice had a Welsh accent so delicate and musical that it sounded as though she were reciting a poem. ‘But we’re qualified to use the probe. We’re both doing research in force microscopy.’
‘And the university couldn’t spare anyone from the faculty,’ Partridge summed up. ‘So William and Kathy kindly agreed to come down to the Smoke for the day and help you out. In exchange for their travelling expenses and a small per diem.’
‘Of course,’ Kennedy said. ‘I’m grateful to you both. Really. This is just wonderful.’ She didn’t think Emil Gassan would object to the extra expense, but if he did, she would meet it herself out of the money she’d already been paid.
‘Let’s go in,’ she suggested. ‘I’ll see about getting you some coffee, and then I’ll explain what it is I need.’
‘We might just as well skip the coffee,’ Partridge suggested, as the two students hefted the steel case by its evenly spaced handles and raised it between them like pallbearers raising a coffin, ‘and get straight down to business.’
But they couldn’t do that without explaining to Gassan, and he was rattled all over again when he realised what he was signing up to. ‘Are we sure that this is legal, Heather?’ he asked, drawing Kennedy aside. ‘It sounds as though it might raise issues of privacy and freedom of information.’
‘These are your premises,’ she explained. ‘All we’re doing is examining them for evidence of unauthorised access. We’re not assuming criminality, only trespass. We’re going to look around Room 37 and find out what was done there. Then when we brace our suspect, we’ll have some ammunition. This was a professional job, Emil. He won’t cave, he’ll stonewall you to the last inch. If you want to have any chance of finding out what happened that night, you’ll need to have a good part of the answer before you ask the question.’
She waited while Gassan thought it through, but she knew she was right and she didn’t have any doubt as to what he’d eventually decide. ‘All right,’ he said at last. ‘Let’s do this.’
At Kennedy’s suggestion, they brought Rush in to help the two students ferry the rest of the components from Partridge’s van. While they were unpacking and setting up, Kennedy tried to explain to Gassan what the probe actually did, but very soon ran into the limits of her own understanding, and Partridge had to come to her rescue.
‘In the 1980s,’ he told Gassan, ‘two Swiss scientists developed a new kind of microscope, one that could scan at an atomic level. They called it AFM, atomic force microscopy. And they did great things with it. It could resolve images down to nanometer scales, with enormous accuracy. The only problem was that the image size, even for a single-pass scan, was colossal. So unless you were looking at incredibly tiny areas, it wasn’t feasible to use an AFM device.’
Away in the background, Kennedy could see Rush standing a little aside from the students. He was helping them whenever they needed him, passing them components from the boxes, holding the main body of the probe steady while Sturdy or Price connected a cable or a bracket to it. It was obvious that he was attracted to Sturdy — and that he had no chance at all because Sturdy and Price were already an item. The follies of youth, Kennedy thought.
She wrenched her attention back to Partridge, who was still talking about the Kelvin probe and its short but illustrious history. ‘But then,’ he said, ‘the University of Swansea got stuck into the original design and started to come up with some really sweet variations. They more or less invented a science called nanopotentiometry. It measures minute changes in electrical potential. The probe looks at the conductivity of an object’s surface. It creates a map of that electrical potential.’