He pushed back his chair.

‘There is, after all, sufficient reason for our silence,’ said Mr Falls.

Something in his attitude, though he had not risen, and some new quality in the tone of his voice, which was a deep one, brought sudden stillness upon his hearers.

‘When one is in danger of arrest,’ said Mr Falls, ‘one does not feel disposed for chatter. May I, however, claim the attention of the company for a moment? Sergeant Webley, will you indulge me?’

Webley, who had made a brusque movement when Gaunt’s chair scraped on the floor, leant the palms of his hands on the table and, looking attentively at Falls, said: ‘Go ahead, sir.’

‘I don’t know,’ said Mr Falls, ‘whether you are all devotees of detective fiction. I must confess that I am. It is argued, in respect of these tales, that they bear little or no relation to fact. Police investigation, we protest, is not a matter of equally balanced motives, tortuous elaborations, and a final revelation in the course of which the investigator’s threat hangs like an ignis fatuus over first one and then another of the artificially assembled suspects. It is rather the slow amassment of fact sufficient to justify the arrest of someone who has been more or less suspect from the moment that the crime was discovered. Sergeant Webley,’ said Mr Falls, ‘will correct me if I am wrong.’

Sergeant Webley cleared his throat sluggishly. One of the men outside the window looked over his shoulder into the room, turned away again, and moved out of sight.

‘However that may be,’ Falls continued, and they listened to him with confused attention as if he had, without warning, thrust an embarrassing ceremony upon them, ‘however that may be, I detect some resemblance in our present assembly to those arbitrary musters, and with the permission of Sergeant Webley I should like, before we break up, to clear the memory of Mr Maurice Questing. Mr Questing was not an enemy agent.’

Here Dr Ackrington broke out with some violence and was not silenced until an account of Questing’s letter had, by a sort of forcible feeding, been rammed down the gullet of his understanding. He took it rather badly. The recovery of Questing’s skull had evidently been broken to him but this final blow to the very corner stone of all his theories seemed literally to horrify him. He turned quite pale, his protestations ceased, and he waited in silence for Falls to go on.