Druce pondered over the question. “No—I can’t say as how”—then a sudden reminiscence seemed to awake in him—“well, sir—now you mention it, there was an incident, so to speak, when Jim Mason come to the—nothing at all important, sir——” he spoke deprecatingly. “Let’s hear it,” rapped Goodall. “Every word of it!” Every vestige of blood went from the night-watchman’s face. “I’m sorry I didn’t think of it before, sir,” he muttered, “I hope there’s no harm done——” “Let’s have it,” bellowed Goodall, “every second’s of importance!” “Well, sir,” said Druce—“it was like this. When I ’eard Jim Mason knock—he give his three knocks just as usual—I went downstairs to let ’im in. When I opened the door he was standin’ there just in the ordinary way—when a female comes up to us. Wanted to know what time the Galleries opened the next morning—that was all she enquired, sir! I told her ‘ten o’clock.’ Then she pointed down the street and asked if that way was the right direction for the Marble Arch.” “And was it?” snapped Goodall eagerly. “Yes,” said Druce with some surprise. “That’s so, sir!” “What did Mason do while this conversation was taking place?” “Mason, sir? He showed ’er the way the same as wot I did.” “Of course he did,” cut in Goodall with decision. “And I expect she wanted a deal of showing, didn’t she?” “She did seem a bit mazed-like,” murmured Druce. “I’ll warrant she did,” said the Inspector. “Just long enough for the murderer to slip in behind your backs and up the stairs in front of Mason.” Druce went goggle-eyed. “Gosh! Who’d ’ave thought of that?” “Not you, evidently,” returned Goodall. “If you had have done, your mate might still be alive. It’s no use, though, wasting time on regrets or recriminations.” He stepped into the private room used by Day as his office. “Is this door locked of an evening when the place closes?” he asked. “Always,” responded Day. “Or, at least, it should be!” “Who was in charge here yesterday evening?” queried the Inspector swiftly. “I was.” Young Forshaw stepped forward. “Did you lock this door when you left?” “To the best of my memory—yes. But it’s a mechanical sort of job—you know, Inspector—the kind of thing you do so often from mere force of habit—that the doing it leaves no very clear impression on your mind.” Goodall nodded in acceptance. He knew exactly what the speaker meant. “Still,” went on Forshaw, “I’m fairly certain I did it.” He thought it over carefully. “How many keys are there?” broke in the Inspector. Day took it upon himself to answer. “Four. Each of the partners has one—and Ronald Forshaw here also. He’s more often in charge here of an evening than anybody—he has to have a key.” “Now tell me again,” interjected Goodall, “who gave the alarm? The cleaner, you said, didn’t you?”