‘We have reason to believe,’ Alleyn went on, ‘that the murder of Lord Robert Gospell is the outcome of blackmail. Did you speak, sir?’

‘No. No! I cannot see, I fail to understand—’

‘I’ll make myself clearer in a moment, I hope. Now, for reasons into which I need not go at the moment, the connection between this crime and blackmail leads us to one of two conclusions. Either Lord Robert was a blackmailer, and was killed by one of his victims, or possibly someone wishing to protect his victim—’

‘What makes you say that?’ asked Carrados hoarsely. ‘It’s impossible!’

‘Impossible? Why, please?’

‘Because, Lord Robert, Lord Robert was not—it’s impossible to imagine—have you any proof that he was a blackmailer?’

‘The alternative is that Lord Robert had discovered the identity of the blackmailer, and was murdered before he could reveal it.’

‘You say this,’ said Carrados, breathlessly, ‘but you give no proof.’

‘I ask you, sir, simply to accept my statement that rightly or wrongly we believe our case to rest on one or the other of those alternatives.’

‘I don’t pretend to be a detective, Alleyn, but—’

‘Just a minute, sir, if you don’t mind. I want you now to go back with me to a day nearly eighteen years ago, when you motored Lady Carrados down to a village called Falconbridge in Buckinghamshire. You were not married then.’

‘I frequently motored her into the country in those days.’

‘You will have no difficulty in remembering this occasion. It was the day on which Captain Paddy O’Brien met with his accident.’

Alleyn waited. He saw the sweat round Carrados’s eyes shine in the strong lamplight.

‘Well?’ said Carrados.

‘You do remember that day?’ Alleyn asked.

‘But Herbert,’ said Lady Carrados, ‘of course you do.’

‘I remember, yes. But I fail to see—’

‘Please, sir! I shall fire point-blank in a moment. You remember?’

‘Naturally.’

‘You remember that Captain O’Brien was taken first to the vicarage and from there, in an ambulance, to the hospital, where he died a few hours later?’

‘Yes.’

‘You remember that, after he died, your wife, as she is now, was very distressed because she believed that a certain letter which Captain O’Brien carried had been lost?’

‘I have no recollection of this.’

‘Let me help you. She said that he had probably carried it in his pocket, that it must have fallen out, that she was most anxious to recover it. Am I right, Lady Carrados?’

‘Yes—quite right.’

Her voice was low, but perfectly steady. She was looking at Alleyn with an air of shocked bewilderment.

‘Did you ask Sir Herbert if he had enquired everywhere for this missing letter?’

‘Yes.’

‘Do you remember now, Sir Herbert?’

‘I think—I remember—something. It was all very distressing. I tried to be of some use; I think I may have been of some use.’

‘Did you succeed in finding the letter?’