When Kerry came to the foot of the stairs, Mollie quite deliberately got in his way, murmured an apology, and gave him a sidelong gaze through lowered lashes, which was more eloquent than any thesis. He smiled with fierce geniality, looked her up and down, and proceeded to mount the stairs, with never a backward glance. His genius for criminal investigation possessed definite limitations. He could not perhaps have been expected in tactics so completely opposed to those which he had anticipated to recognize the presence of a valuable witness. Student of human nature though undoubtedly he was, he had not solved the mystery of that outstanding exception which seems to be involved in every rule. Thus, a fellow with a low forehead and a weakly receding chin, Kerry classified as a dullard, a witling, unaware that if the brow were but low enough and the chin virtually absent altogether he might stand in the presence of a second Daniel. Physiognomy is a subtle science, and the exceptions to its rules are often of a sensational character. In the same way Kerry looked for evasion, and, where possible, flight, on the part of one possessing a guilty conscience. Mollie Gretna was a phenomenal exception to a rule otherwise sound. And even one familiar with criminal psychology might be forgiven for failing to detect guilt in a woman anxious to make the acquaintance of a prominent member of the Criminal Investigation Department. Pausing for a moment in the entrance of the club, and chewing reflectively, Kerry swung open the door and walked out into the street. He had one more cover to “beat,” and he set off briskly, plunging into the mazes of Soho crossing Wardour Street into old Compton Street, and proceeding thence in the direction of Shaftesbury Avenue. Turning to the right on entering the narrow thoroughfare for which he was bound, he stopped and whistled softly. He stood in the entrance to a court; and from further up the court came an answering whistle. Kerry came out of the court again, and proceeded some twenty paces along the street to a restaurant. The windows showed no light, but the door remained open, and Kerry entered without hesitation, crossed a darkened room and found himself in a passage where a man was seated in a little apartment like that of a stage-door keeper. He stood up, on hearing Kerry’s tread, peering out at the newcomer. “The restaurant is closed, sir.” “Tell me a better one,” rapped Kerry. “I want to go upstairs.” “Your card, sir.” Kerry revealed his teeth in a savage smile and tossed his card on to the desk before the concierge. He passed on, mounting the stairs at the end of the passage. Dimly a bell rang; and on the first landing Kerry met a heavily built foreign gentleman, who bowed. “My dear Chief Inspector,” he said gutturally, “what is this, please? I trust nothing is wrong, eh?” “Nothing,” replied Kerry. “I just want to look round.”