‘I am,’ said the wine merchant, nervously.

‘Then I want the rest of my money.’

‘Who are you?’

‘I’m the person you hired to kill Sir Roger Mellanby,’ said the other, ‘and I obeyed my instructions. Instead of paying me my full fee, you ordered someone to have me killed.’

‘I did nothing of the kind.’

‘That person is no longer alive, and neither is the one who tried to shoot me dead in St James’s Park.’

‘Please believe me,’ cried Denley. ‘I don’t know what you’re talking about.’

‘Yes, you do,’ said Peter.

‘Keep out of this,’ ordered the assassin.

‘But I came here to accuse Mr Denley of having blood on his hands.’

‘He’ll have it all over him by the time I’ve finished with him. Stand back,’ he added as Peter took a step towards him. ‘I can shoot just as well with either hand.’

He produced a second pistol from inside his coat and pointed towards Peter who took a step backwards. Denley was trembling with fear but Peter remained calm and watchful. He was surprised how young and elegant the assassin was.

‘Open that safe,’ demanded the newcomer.

‘You’re making a terrible mistake,’ said Denley. ‘Whoever told you that I was implicated in the murder was lying.’

‘The person who told me was you.’

‘That’s impossible.’

‘I have your letter to prove it.’

He tucked one of the pistols under his arm so that he could take the letter out of his pocket. When he’d slapped it down on the desk, he grabbed the other pistol again and kept it trained on Peter. Denley was frozen with horror. He couldn’t even bear to look at the letter.

‘Read it out,’ snarled the assassin. ‘Pick it up and read it out.’

Shaking all over, Denley picked up the letter and forced himself to look at it. His manner suddenly changed completely. Relief flooded through him.

‘I didn’t write this,’ he said.

‘Don’t lie to me,’ warned the assassin. ‘It has your name on it – Denley.’

‘Yes,’ interjected Peter, realising what must have happened, ‘but it may not be Mr Denley. Unless I’m mistaken, that letter was signed by his wife.’

‘It was,’ confirmed Denley. He opened a drawer. ‘I’ll show you. I have other letters from my wife.’ Pulling out a sheaf of correspondence, he picked out a letter. ‘Look at her signature. It’s identical to the one in your letter.’