‘Where do you think you are,’ Sergeant Caine said, shaking his head with disbelief, ‘Madame Tussaud’s? This is a training facility for officers who put themselves in harm’s way. Not a freak show.’

‘I just want to see the letter.’

‘What makes you think it’s here?’

‘I just don’t believe it was lost. I can’t believe that. The only letter from Jack the Ripper? Come on. I think it would have been filed, saved, preserved.’

‘Why lie about it?’

‘Don’t want the public getting too excited about some unholy relic, do we? Don’t need them turning a serial killer into a bigger cult hero than he is already. But I think we would have saved it.’

‘We?’

‘The law. The Met. The good guys. And I think that if it is anywhere in London, then it will be in some secret corner of the Black Museum.’

He laughed. ‘I suppose you might just make a detective one day. But why do you want to see it – assuming it’s in my power to show it to you?’

‘I want to see what the real thing looks like.’

He moved towards the door and I thought he was going to call for some help and have me kicked out. But Sergeant Caine wouldn’t have needed any help to kick me out.

I watched him lock Room 101.

‘There were hundreds of letters claiming to be from Jack the Ripper,’ he said. ‘The Dear Boss letter. The Saucy Jacky postcard. The Openshaw letter. What made the From Hell letter different was that, as you say, it came with a small box containing half a human kidney.’

I watched him remove a calendar from the wall that said MERRY CHRISTMAS AND A HAPPY NEW YEAR FROM THE METROPOLITAN POLICE.

There was a safe in the wall.

‘Turn away, detective,’ he said, and I turned my head as he tapped some numbered keys. ‘It was addressed to George Lusk, the head of the Whitechapel Vigilance Committee. You can turn back now.’

There was a dark green folder on his desk.

He opened it. Inside the folder was a plastic envelope. Inside the envelope was a single sheet of paper, rust-coloured with age, as brittle as something scorched, like something pulled from the fire at the very last moment.

Large red letters, a dozen lines, words written quickly, words written in a fever.

‘Somebody slung out the kidney,’ Sergeant Caine said. ‘Sorry about that.’

From hell

Mr Lusk

Sor

I send you half the

Kidne I took from one women

Prasarved it for you tother piece

I fried and ate it was very nice, I

may send you the bloody knif that

took it out if you only wate a whil

longer.

Signed

Catch me when

You Can

Mishter Lusk

‘It’s real, isn’t it?’ I said. ‘You can tell. It’s from him. It’s from Jack the Ripper.’