The silence felt worse once the phone call was done, and, after a minute, Hanson leaned forwards and pressed the button for the radio. ‘Are you OK with Radio Four?’

‘Sure,’ Lightman said, equably. ‘Whatever you like.’

Louise Reakes’s manner was a little defiant. She seemed genuinely outraged to be back in the station. But Jonah was certain he detected a note of panic beneath the affront.

‘I don’t understand why I’m here,’ she said to Jonah, as soon as the tape was running. O’Malley, alongside him, was tapping on a laptop, and Louise gave him a look of irritation before she gazed back at Jonah.

‘You’re here because we think you lied to us,’ Jonah told her.

‘I’ve told you nothing but the truth,’ she said. And yet Louise looked close to breaking. It was clear that she was hiding something from them.

‘What about when you told us you didn’t know the victim?’

Louise gave him a look that seemed genuinely confused. She glanced towards O’Malley, who gave her his warmest smile.

‘I didn’t know him,’ she said, after a beat. ‘There’s nothing untrue in that.’

‘My sergeant is going to show you a video clip taken from the entrance to a club called Blue Underground,’ Jonah said. He could see the sudden step up in tension in Louise’s body.

He turned towards the side wall, where the ceiling-mounted data projector shone its image. As a bright rectangle lit up across the wall, O’Malley rose and dimmed the lights.

The CCTV footage began, a moving version of what Jonah had seen once before, but just as silent. Just as grey-scaled. Just as stark.

Louise Reakes appeared, with the fixed gaze and wavering gait of the very drunk.

‘This is you leaving Blue Underground at just before one twelve a.m.,’ O’Malley said, his voice still affable. It jarred with the starkness of the image.

Even in the dim light it was obvious that this had hit Louise hard.

‘Oh my God, I’m …’ She gave Jonah a slightly desperate look. ‘I don’t remember leaving the house. She – we must have decided to go out. I’m so sorry …’

Jonah looked back at the screen, and asked O’Malley to rewind it and play it again.

‘I can’t see any sign of April Dumont in this image.’

There was a brief silence, and then Louise said, ‘No.’

‘When did April go home?’

‘I don’t know,’ Louise said, unsteadily. ‘I don’t remember any of it. I thought I’d stayed at home. Like I told you.’

O’Malley paused the image as Louise was about to vanish off screen, and they both waited, looking at Louise instead of the projection.

‘Maybe I felt too drunk, and left,’ she said. ‘Or … I guess she could have been … with a guy.’

Neither Jonah nor O’Malley said anything.