“He was afraid, then, of something or someone linked in his mind with the word Fire-Tongue.  What do we know about Fire-Tongue?  One thing only:  that it had to do with some episode which took place in India.  This item we owe to Nicol Brinn.

“Very well.  Sir Charles believed himself to be in danger from some thing or person unknown, associated with India and with the term Fire-Tongue.  What else?  His house was entered during the night under circumstances suggesting that burglary was not the object of the entrance.  And next?  He was assaulted, with murderous intent.  Thirdly, he believed himself to be subjected to constant surveillance.  Was this a delusion?  It was not.  After failing several times I myself detected someone dogging my movements last night at the moment I entered Nicol Brinn’s chambers.  Nicol Brinn also saw this person.

“In short, Sir Charles was, beyond doubt, at the time of his death, receiving close attention from some mysterious person or persons the object of which he believed to be his death.  Have I gone beyond established facts, Innes, thus far?”

“No, Mr. Harley.  So far you are on solid ground.”

“Good.  Leaving out of the question those points which we hope to clear up when the evidence of Miss Abingdon becomes available—­how did Sir Charles learn that Nicol Brinn knew the meaning of Fire-Tongue?”

“He may have heard something to that effect in India.”

“If this were so he would scarcely have awaited a chance encounter to prosecute his inquiries, since Nicol Brinn is a well-known figure in London and Sir Charles had been home for several years.”

“Mr. Brinn may have said something after the accident and before he was in full possession of his senses which gave Sir Charles a clue.”

“He did not, Innes.  I called at the druggist’s establishment this morning.  They recalled the incident, of course.  Mr. Brinn never uttered a word until, opening his eyes, he said:  ’Hello!  Am I much damaged?’”

Innes smiled discreetly.  “A remarkable character, Mr. Harley,” he said.  “Your biggest difficulty at the moment is to fit Mr. Nicol Brinn into the scheme.”

“He won’t fit at all, Innes!  We come to the final and conclusive item of evidence substantiating my theory of Sir Charles’s murder:  Nicol Brinn believes he was murdered.  Nicol Brinn has known others, in his own words, ‘to go the same way.’  Yet Nicol Brinn, a millionaire, a scholar, a sportsman, and a gentleman, refuses to open his mouth.”

“He is afraid of something.”

“He is afraid of Fire-Tongue—­whatever Fire-Tongue may be!  I never saw a man of proved courage more afraid in my life.  He prefers to court arrest for complicity in a murder rather than tell what he knows!”

“It’s unbelievable.”

“It would be, Innes, if Nicol Brinn’s fears were personal.”

Paul Harley checked his steps in front of the watchful secretary and gazed keenly into his eyes.