Du Maurier poured water into his absinthe. ‘It’s all possible,’ he said. ‘Personally I like the idea of blackmail. It answers many questions. Though not all of them. If, for example, Slater had been blackmailing our friend for some time, where is the rest of the money? He certainly didn’t bank it, either here or in England. There was no money in the apartment, though it is possible that money was removed from the safe by your intruder. But somehow I don’t think so. It seems to me that if blackmail was the motive for murder, then the evidence is what was removed from the safe. So, if there was more money, where is it?’

‘A numbered account in Switzerland.’

‘Again, possible, but I think not. There would have been records somewhere among his personal belongings.’

Bannerman took a slug of whisky. ‘Seems like you’ve been busier than me.’

Du Maurier smiled and ran a hand through the remains of black, wiry hair. ‘More importantly,’ he said, ‘blackmail does not furnish us with any motive for murder by a third party.’

‘Someone else who felt threatened?’ Bannerman suggested. ‘If Slater had dirt on Gryffe, then perhaps some of that dirt might have stuck to others.’

The policeman scratched his chin. ‘Assuming that was true,’ he said thoughtfully, ‘would the murderer have left the money behind?’ He sighed. ‘There is little point, Monsieur Bannerman, in speculating. We could talk around the subject all night and only create for ourselves more questions that we cannot answer.’ He emptied his glass.

Bannerman placed a hand on his arm once more. ‘One final question. Gryffe had another place in Brussels. Where?’

The Inspector frowned. ‘He had no other apartment in Brussels, Monsieur Bannerman. Only in the Rue de Pavie.’

Bannerman shook his head. ‘Then you are not as thorough as you might have been,’ he said. ‘Slater lists two home numbers in Brussels for Gryffe. They are in his contacts book. Presumably one of them is the Rue de Pavie.’ He took out his notebook and flipped through to the page where he had noted the numbers, and pushed it across the table at du Maurier.

The other man’s frown deepened. ‘The first number is the Rue de Pavie,’ he said. ‘What makes you think the second number is Belgian?’

‘It was preceded by the Belgian country-code, thirty-two.’

Du Maurier looked again at the number. ‘It is not a Brussels area code. Somewhere provincial, perhaps.’ He took out a small black notebook and a pen and copied the number into it. ‘I will check.’ He scribbled another number on a fresh page, tore it out and handed it to Bannerman. ‘If you need to call me, phone that number. Speak to no one else but me. Do not come to the Rue des Quatre Bras.’

Bannerman took it and folded it into his top pocket. He said, ‘I’ll want Slater’s car from the pound.’