‘Filthy pictures?’

‘Anything but.’ After washing hands and sharing the noisy blow dryer they emerged into the corridor, where Rainy Macintosh eyed them up and down. ‘Having a wee meeting, boys?’

‘You’ll go down for a long stretch one day,’ Gillard said, laughing.

Perry led him to his desk, and dragged over a chair to let Gillard sit side-by-side at the screen on his PC.

‘This is the mystery girl, recovered from our yellow Allegro submarine. Photographs taken by CSI.’

Gillard nodded. He’d seen those pictures before from the Skype meeting with Dr Delahaye: the innocent teenager in her cardigan and fawn tights.

Perry clicked to the next image, which came up side-by-side. ‘And this is Jane Morris, the picture circulated at the time of her disappearance.’

Gillard’s jaw hung open. He looked from one to the other. They were identical, apart from the 1980s hairstyle on the old picture. Even the clothing looked identical. Same cardigan and tights.

‘It’s not possible, is it?’ Perry said.

‘When we talked earlier I had thought identical twins…’

‘They wouldn’t be identical now, would they?’ Perry said. ‘Jane Morris’ twin would be fifty-two now. The DNA test was rechecked, and it comes back that this is the very same woman who went missing in 1982 at the age of fifteen. They look the same, and forensics say they are the same.’

Gillard shook his head. ‘It’s weird that the car was made in the same year Jane Morris disappeared. You might imagine she’s been sitting dead in the passenger seat since 1982, except that she’s way better preserved than the car.’

Perry scratched his head. ‘Anyway, that’s my mystery.’

Gillard blew a sigh. ‘There’s another complication. If that yellow Allegro is a time machine, it seems Beatrice Ulbricht has been in it too. I recovered some hairs entangled around the brake and clutch pedals which turned out to be hers. I suppose they had got caught when the vehicle was inverted during the flood, and her head was being jostled into the footwell.’

‘How on earth did Jane Morris and Beatrice Ulbricht end up in the same car?’ Perry asked.

Gillard stroked his chin. ‘If your body is also the impostor on the train, then it’s possible Beatrice’s hair was on the coat she used. I think it’s quite a neat idea.’

‘But that doesn’t square with her being Jane Morris. Someone magicked out of the past to commit a crime in the present. It’s not possible.’

‘Claire Mulholland is convinced the perpetrator is a woman,’ Gillard said. ‘Maybe two women.’

‘Okay, I’m all for female empowerment,’ said Perry. ‘But whether she’s right or wrong we’ve still got the same problem.’

Gillard tapped his fingers on the desk. ‘There’s only one answer. It is Jane Morris, the DNA and the resemblance can’t both be wrong. But we have to explain how the corpse is so well preserved after nearly four decades.’

‘Freezer?’

‘No. I worked on the Franklin case in Esher back in 2009, where the wife had kept the dead husband in her freezer in the garage for eighteen months. Once forensics thawed him out he looked in a far worse state that Jane Morris does. There’s a reason why you’re supposed to eat frozen food within three months.’