He ripped open the flap of the envelope and took out a memo sheet. He read the few lines of typescript and then folded the sheet precisely. Glancing at me he hesitated before saying, ‘Mrs Salton is back at El Cerco.’

‘Is she, by God?’ I could do with seeing her again. ‘I’m afraid I’ll need my car.’

‘No,’ said Hanna. ‘Remember the sight lines.’ He frowned and I noticed that the lines of strain were beginning to re-appear. Apparently he was juggling with a decision. ‘As far as I’m concerned, Mrs Salton is one of the most delicate areas of this investigation. I have to walk very soft-footed at El Cerco.’ He chewed his lower lip. ‘That’s why I’m going to let you go out there. You can ask questions which I can’t.’

‘What do you want to know?’

‘I want to know about the quarrel the Saltons had. Maybe you can surprise it out of her.’

‘I can try.’ I wasn’t too keen on the idea of doing Hanna’s dirty work for him, but my own curiosity was raging in my brain.

He dug his hand in his pocket and produced a car key. ‘Take my car. We’re still going by the book.’

‘Thanks,’ I said, and turned away.

‘One more thing,’ he said. ‘When you’re at El Cerco, remember that pressure I mentioned.’

For a straightforward copper who did things by the book, he could be bloody enigmatic.

As I pulled Hanna’s car away from the kerb, I glanced in the rear-view mirror and saw him talking to the policeman, who had remounted his motorcycle. The policeman followed me all the way to the northern tip of the island at a tactful distance of two hundred yards.

At El Cerco the gates were closed and the same two men on duty. The one on the outside came forward and stooped to look at me. ‘Mr Kemp to see Mrs Salton,’ I said.

He straightened and took a sheet of paper from his breast pocket. After scanning it, he said. ‘You’re not on the list.’

‘Have you a telephone? I’d like to speak to Mrs Salton.’

He gave me a long unsmiling look. ‘Wait here.’ He walked back to the gate and spoke to the man inside. I turned my head and looked back along the road. The policeman on the motorcycle had stopped two hundred yards back and was waiting quietly.

Presently the gates opened and the guard waved me through. As I stepped on the accelerator I checked the mirror. The policeman made no move but waited unobtrusively. It seemed as though I had a guard of my own.