“Mr. Theydon,” he said, at last, halting in front of the younger man and gazing down at him with a direct intensity that was highly embarrassing to one who had good cause to connect him with the actual crime.  “I want you to do me a favor—­ a great favor.  It was in my mind at first to ask you to permit me to go with you to Innesmore Mansions, and to be present during the interview with the detectives.  But a man in my position must be circumspect.  It would, perhaps, be unwise to appear too openly interested.  I don’t mind telling you in confidence that I have known Mrs. Lester many years.  The shock of her death, severe as it must have been to you, is slight as compared with my own sorrow and dismay.  More than that I dare not say until better informed.  I remember now hearing the newsboys shouting their ghoulish news, and I saw contents bills making large type display of ’Murder of a lady,’ but little did I imagine that the victim was one whom—­ one whose loss I shall deplore....  Are you on the telephone?”

“Yes,” said Theydon, thoroughly mystified anew by the announcement that Forbes had even contemplated, or so much as hinted at, the astounding imprudence of visiting Innesmore Mansions that night.

“Ring me up when the detectives have gone.  I shall esteem your assistance during this crisis as a real service.”

For the life of him, Theydon could not frame the protest which ought to have been made without delay and without hesitation.

“Yes,” he said.  “I’ll do that.  You can trust me absolutely.”

Thus was he committed to secrecy.  That promise sealed his lips.

CHAPTER III

 In the toils

Theydon, though blessed, or cursed, with an active imagination—­ which must surely be the prime equipment of a novelist—­ was shrewd and level-headed in dealing with everyday affairs.

It was no small achievement that the son of a country rector, aided only by a stout heart, a university education and an excellent physique—­ good recommendations, each and all, but forming the stock-in-trade of many a man on whose subsequent career “failure” is writ large—­ should have forced himself to the front rank of the most overcrowded among the professions before attaining his twenty-sixth year.

It may be taken for granted, therefore, that he was not lacking in the qualities of close observation and critical analysis.  He would, for instance, be readier than the majority of his fellows to note the small beginnings of events destined to become important.

Often, of course, his deductions would prove erroneous, but the mere fact that he habitually exercised his wits in such a way rendered it equally certain that his judgment would be accurate sometimes.  One such occasion presented itself a few seconds after he had left the Forbes mansion.

A taxi, summoned by a footman, was in waiting, and Theydon was crossing the pavement when he noticed a gray landaulet car at rest beneath the trees at some distance.  Mr. Forbes’s house stood in a square, and the gray car had been drawn up on the quiet side of the roadway, being stationed there, apparently, to await its owner’s behest.  Gray cars are common enough in London, but they are usually of the touring class.