‘The police will tell us that. But we can assume that he went to the Snuggery sometime between ten past nine, which is when he talked to his wife, and ten o’clock, when Marc Bellamy noticed he was missing.’

Hawthorne had been examining the ground. Suddenly, he stopped and pointed. He had found a footprint in a patch of sand just at the foot of the path leading up to the Snuggery. I couldn’t say for sure, but the perfect curve of the toecap looked remarkably similar to the bloody footprint we had found near the body.

‘You’re right, Hawthorne!’ I exclaimed. ‘I don’t know how you do it. But it’s perfectly clear.’ I looked up at the Snuggery. ‘Someone unlocked the door. They had an accomplice who climbed up from the beach. The two of them hit le Mesurier on the head and forced him into the chair. And after they’d killed him, they separated and each went their own way.’

‘It could have happened like that.’ Why did Hawthorne have to sound so unsure when it was perfectly obvious to me? ‘But there’s a problem.’

‘What problem?’

‘Well, for the whole thing to work the way you just described – one inside, one outside – they’d have to know that le Mesurier was planning to visit the Snuggery and at what time.’

‘They could have texted from the house.’

Hawthorne took out his phone and looked at it. ‘No signal.’

I did the same and sighed. ‘Mine too.’

‘Your set-up only works if the accomplice is already there and waiting before le Mesurier arrives – maybe hidden behind one of those curtains. Le Mesurier comes in with someone and that’s when the two of them incapacitate him and force him into the chair. They tie him up – we still don’t know why – and then they kill him.’

‘Suppose they unlocked the door earlier? Someone could have climbed up from the beach and hidden behind the curtains. They could have been inside the Snuggery all evening.’

‘They’d still have to be sure that le Mesurier would go in there. And on his own . . .’

Hawthorne was still holding his mobile phone. He took a photograph of the footprint.

‘Are you going to tell Torode about this?’ I asked.

‘I’m sure he’ll find it for himself, but I’ll send him a picture if you think it will make him happy.’

He slipped the phone back into his pocket and was about to leave, but I stopped him. ‘Hawthorne,’ I said. ‘There’s something you’ve got to tell me.’

‘What’s that, mate?’