"It simplifies things a good deal from our point of view," returned the Inspector. "Directly we can get a crime into a particular class we're half way toward finding the man who did it. You see, there are never more than a certain number of skilled burglars out of prison, and it's the Yard's business to keep a pretty close eye on what they're up to. Roughly speaking, a case like this narrows itself down to about twenty or thirty likely parties. By to-night they'll all have been put through it, and if there's a single one who can't account exactly for what he was doing he'll--well, he'll be what the newspapers call 'detained for further inquiries.' "Do you think it was the same man who broke in before?" asked Colin. Marsden looked doubtful. "It may be, of course, and if that's so there's probably more in the case than appears on the surface. A man like the Professor might very well have had papers and secrets that certain people were anxious to get hold of, and it's quite on the cards that they might have taken in a professional thief to do their dirty work for them. The trouble is that at present we know practically nothing about his private life." "I can't help you there," said Colin. "I believe that Mr. Medwin was the only person who was at all in his confidence." "Well, Mr. Medwin will be able to answer for himself in a few minutes. Our next best hope is to get on to the track of this old manservant Kennedy. He seems to have been with the Professor for about forty years, so if he's still alive he might be able to give us some useful information." "I expect Mrs. Ramsay or the cook could let you have his address." "I asked them last night, but neither of them has the least notion where he is. From the way they spoke I gather that there was precious little love lost between them. However, he will probably show up as soon as he reads about the murder, and, if not, we oughtn't to have much difficulty----" A ring at the front door bell interrupted his words, and, glancing at the clock, he gulped down the remainder of his tea. "I wonder if this is our man," he added. "You don't often find a solicitor ahead of his time." He turned to Colin as Mrs. Ramsay's steps were heard crossing the hall. "Just a word of caution, doctor. He knows nothing about the murder yet, and I've told the old lady to keep her tongue quiet while she's showing him in. Leave me to break the news if you will; I've a fancy to see how he takes it." Colin's only reply was a nod, and the three of them sat in silence until the door opened and Mrs. Ramsay appeared on the threshold, with the massive form of Mr. Medwin looming up behind her. The solicitor, who was wearing a frock-coat and carrying a top hat in his hand, took a couple of paces forward. Then with an air of surprise he came to a sudden halt. The Inspector rose instantly. "Let me introduce myself, Mr. Medwin. I am Inspector Marsden, of Scotland Yard."