‘Well?’ asked Nightingale.

‘A dog,’ I said. ‘A little yappy dog.’

Growling, barking, yelling, flashes of cobbles, sticks, laughing — maniacal, high-pitched laughing.

I stood up sharply.

‘Violence and laughter?’ asked Nightingale. I nodded.

‘What was that?’ I asked.

‘The uncanny,’ said Nightingale. ‘It’s like a bright light when you close your eyes, it leaves an afterimage. We call it vestigium.’

‘How do I know I didn’t just imagine it?’ I asked.

‘Experience,’ said Nightingale. ‘You learn to distinguish the difference through experience.’

Thankfully we turned our back on the body and left.

‘I barely felt anything,’ I said, while we were changing. ‘Is it always that weak?’

‘That body’s been on ice for two days,’ said Nightingale, ‘and dead bodies don’t retain vestigia very well.’

‘So whatever caused it must have been very strong,’ I said.

‘Quite,’ said Nightingale. ‘Therefore we have to assume that the dog is very important and we have to find out why.’

‘Maybe Mr Skirmish had a dog,’ I said.

‘Yes,’ said Nightingale. ‘Let’s start there.’

We’d changed and were on our way out of the mortuary when fate caught up with us.

‘I heard rumours there was a nasty smell in the building,’ said a voice behind us. ‘And bugger me if it isn’t true.’

We stopped and turned.

Detective Chief Inspector Alexander Seawoll was a big man, coming in a shade under two metres, barrel-chested, beer-bellied and with a voice that could make the windows shake. He was from Yorkshire, or somewhere like that, and like many Northerners with issues, he’d moved to London as a cheap alternative to psychotherapy. I knew him by reputation, and the reputation was, don’t fuck with him under any circumstances. He bore down the corridor towards us like a bull on steroids, and as he did I had to fight the urge to hide behind Nightingale.