‘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.

‘This is my fucking investigation, Nightingale,’ said Seawoll. ‘I don’t care who you’re currently fucking – I don’t want any of your X-Files shit getting in the way of proper police work.’

‘I can assure you, Inspector,’ said Nightingale, ‘I have no intention of getting in your way.’

Seawoll turned to look at me. ‘Who the hell is this?’

‘This is PC Peter Grant,’ said Nightingale. ‘He’s working with me.’

I could see this shocked Seawoll. He looked at me carefully before turning back to Nightingale. ‘You’re taking on an apprentice?’ he asked.

‘That’s yet to be decided,’ said Nightingale.

‘We’ll see about that,’ said Seawoll. ‘There was an agreement.’

‘There was an arrangement,’ said Nightingale. ‘Circumstances change.’

‘Not that fucking much they don’t,’ said Seawoll, but it seemed to me he’d lost some of his conviction. He looked down at me again. ‘Take my advice, son,’ he said quietly. ‘Get the fuck away from this man while you still have a chance.’

‘Is that all?’ asked Nightingale.

‘Just stay the hell away from my investigation,’ said Seawoll.

‘I go where I’m needed,’ said Nightingale. ‘That’s the agreement.’

‘Circumstances can fucking change,’ said Seawoll. ‘Now if you gentlemen don’t mind, I’m late for my colonic irrigation.’

He went back up the corridor, crashed through the double doors and was gone.

‘What’s the agreement?’ I asked.

‘It’s not important,’ said Nightingale. ‘Let’s go and see if we can’t find this dog.’