Corinne Edgerton nodded, a little dubiously. ‘We can take a look at the car park CCTV, but we don’t have a lot of coverage there. Our main cameras are above the aisles, looking down for shoplifters – and monitoring our staff, too.’ She smiled. ‘Let’s go up to the CCTV room and see what we have from yesterday, both outside and inside. We should certainly pick up this lady inside the store, if not outside also.’

For the next thirty minutes, Grace and Branson sat with Edgerton in front of the bank of monitors, in the small room one floor up from the public area of the store. They watched all recordings from each camera, firstly those covering outside, and then those covering the aisles, from fifteen minutes before the time that Niall Paternoster had claimed he’d driven into the car park and his wife had jumped out of the car to dash into the store, until half an hour after the store had closed.

The exterior cameras scanning a limited area of the car park had recorded no sign of the Paternosters’ black BMW entering. But that did not mean it hadn’t – it was a vast area and with only limited CCTV coverage. Grace had been hoping to see footage of Eden Paternoster getting out of the car, which would have established that her husband had been telling the truth.

The cameras covering the front entrance of the store had not shown her either, neither entering nor leaving. And she had not appeared on any of the cameras that were strategically sited to monitor the aisles in the store. There were a dozen cameras covering the vast interior space. With Edgerton operating the control sticks, they forwarded slowly through each of them in turn, occasionally zooming in on anyone who remotely fitted Eden’s description and freezing the image while they checked against her photograph. But finally they were satisfied, supported by the fact that no one working in the store had seen her, that there was no evidence she had been here at the time her husband had said.

‘Would it be possible, Corinne,’ Grace asked, ‘for her to have entered the store any other way?’

She thought for a moment. ‘The lady could have come in via the staff entrance at the rear, but she’d have had to have known the key code.’

‘How often do you change that?’ Branson asked.

‘God, probably not often enough. I’ve been here five years and we’ve only changed it a handful of times.’

Grace gave her a reproachful look.

She smiled. ‘I know, mea culpa!’

‘So that is a possibility?’ Grace asked.

She shook her head adamantly. ‘If she was in this store, she would have been picked up on one of the cameras. No question. And you’ve seen the one almost directly above the cat litter – animal products – section.’

Either, Roy Grace thought, Eden Paternoster had never entered the store at the time her husband claimed, or—