He was right, of course. She should probably have sent a patrol officer to take the statement—then if anything needed to be followed up on, she could have opened an investigation. But so much was lost in the transcription. She liked to be able to look into the faces of complainants, to see the things they chose not to say. The length of pauses. The guilty glances. Lauren Tranter wasn’t guilty of anything, but Harper could have filled a notebook with the things she did not say.

Giving an innocent smile, she tapped the pile of papers in her in-tray. “I’m on it now sir, don’t you worry.”

She swivelled to face her computer monitor, which lit up at a flick of the mouse. From the corner of her eye she observed the senior officer as he stood in the doorway, before sighing deeply, shaking his head and then walking away.

The instant he was out of sight she searched in her satchel, found the disk she’d picked up from security at the hospital and pushed it into the computer. After a few seconds, a grainy image of a hospital corridor appeared. The clock at the bottom right-hand corner of the screen read 03.38. There was the nurse’s station, and there was the midwife, Anthea Mallison, in the exact same pose she’d been in when Harper had met her in person, hunched in front of the monitor. The green and white hue of the CCTV footage showed her face illuminated behind the desk by the glow from the computer screen.

She watched for a while. Nothing happened except the clock slowly marking the minutes.

Harper forwarded the video to 04.15. There. Something ran across the floor, taking the same route that Harper herself had taken earlier in the day, towards the bay where Mrs Tranter and Mrs Gooch were installed, bay three. She backed up the video and ran it again. A flash of something, rodent-like, blink and you’d miss it. The midwife kept her eyes on the screen and didn’t flinch. There seemed to be a streak of them, whatever they were—more than one, anyway, flowing past the nurse’s station. They’d have been right in her eye line. On the screen, Mallison made no reaction whatsoever.

Harper examined the section frame by frame, stopping it where three blurred smudges swam across the floor. The way they flickered, caught between two frames, they looked like big black fish. Shadows of fish. Maybe they were shadows, something flying across the light above rather than on the floor—that might also explain why Mallison didn’t react. They might have been moths, or big flies or something. Harper watched it again, in real time. She shook her head, watched it once more. It could easily have been a blip; a digital anomaly, nothing at all. So why did she feel the hair rise on the back of her neck?