“I’ll answer your question,” said Wessex, and the fact did not escape the keen observing power of Nicol Brinn that the detective’s manner had grown guarded. “He informed Mr. Innes, his secretary, before setting out, that he was coming here to your chambers.” Nicol Brinn stared blankly at the speaker. “He told him that? When?” “Yesterday.” “That he was coming here?” “He did.” Nicol Brinn sat down again upon the settee. “Detective Inspector,” said he, “I give you my word of honour as a gentleman that I last saw Mr. Paul Harley at ten-fifteen on Wednesday night. Since then, not only have I not seen him, but I have received no communication from him.” The keen glance of the detective met and challenged the dull glance of the speaker. “I accept your word, sir,” said Wessex, finally, and he sighed and scratched his chin in the manner of a man hopelessly puzzled. Silence fell again. The muted sounds of Piccadilly became audible in the stillness. Cabs and cars rolled by below, their occupants all unaware of the fact that in that long, museum-like room above their heads lay the key to a tragedy and the clue to a mystery. “Look here, sir,” said the detective, suddenly, “the result of Mr. Paul Harley’s investigations right up to date has been placed in my hands, together with all his notes. I wonder if you realize the fact that, supposing Mr. Harley does not return, I am in repossession of sufficient evidence to justify me in putting you under arrest?” “I see your point quite clearly,” replied Nicol Brinn. “I have seen my danger since the evening that Mr. Paul Harley walked into this room: but I’ll confess I did not anticipate this particular development.” “To get right down to business,” said Wessex, “if Mr. Paul Harley did not come here, where, in your idea, did he go?” Nicol Brinn considered the speaker meditatively. “If I knew that,” said he, “maybe I could help. I told him here in this very room that the pair of us were walking on the edge of hell. I don’t like to say it, and you don’t know all it means, but in my opinion he has taken a step too far.” Detective Inspector Wessex stood up impatiently. “You have already talked in that strain to Mr. Harley,” he said, a bit brusquely. “Mr. Innes has reported something of the conversation to me. But I must ask you to remember that, whereas Mr. Paul Harley is an unofficial investigator, I am an officer of the Criminal Investigation Department, and figures of speech are of no use to me. I want facts. I want plain speaking. I ask you for help and you answer in parables. Now perhaps I am saying too much, and perhaps I am not, but that Mr. Harley was right in what he believed, the circumstances of his present disappearance go to prove. He learned too much about something called Fire-Tongue.”