I heard Toby bark, and suddenly Nicholas wasn’t there any more.

‘You’re not making any friends here, Nicholas,’ I said.

Nightingale returned with Toby, and with nothing to report. I didn’t tell him about the ghost or what the ghost had said about him. I feel it’s important not to burden your senior officers with more information than they need.

I picked up Toby and held him so that his absurd doggy face was level with mine — I tried to ignore the smell of PAL Meaty Chunks in gravy.

‘Listen Toby,’ I said, ‘your master is dead, I’m not a dog person and my governor would turn you into a pair of mittens as soon as look at you. You’re looking at a one-way ticket to Battersea Dog’s Home and the big sleep. Your one chance to avoid the big kennel in the sky is to use whatever doggy supernatural senses you have to track … whatever it was murdered your owner. Do you understand?’

Toby panted and then barked once.

‘Close enough,’ I said, and put him down. He immediately trotted over to the pillar and lifted his leg.

‘I wouldn’t turn him into a pair of mittens,’ said Nightingale.

‘No?’

‘He’s a short-haired breed — they’d look terrible,’ said Nightingale. ‘Might make a good hat.’

Toby snuffled around a spot close to where his master’s body had lain. He looked up, barked once and shot off towards King Street.

‘Damn,’ I said. ‘I wasn’t expecting that.’

‘Get after him,’ said Nightingale.

I was already on my way. Detective Chief Inspectors don’t run — that’s what they have constables for. I sprinted after Toby who, like all rat-like dogs, could really shift when he wanted to. Past the Tesco’s he went, and down New Row with his little legs whirring like a low-budget cartoon. Two years running down drunks in Leicester Square had given me some speed and stamina, and I was gaining when he crossed St Martin’s Lane and into St Martin’s Court on the other side. I lost ground when I had to dodge around a crocodile of Dutch tourists leaving the Noël Coward Theatre.