But Hughes was a man of bull-dog grit and perseverance. He argued that a mysterious murder had been committed and the mystery had to be solved and the murderer punished. That was all there was about it. So, to work. And his work began, in accordance with the dictates of his judgment, in the cellar of Ursula Pell's house. And it ended there, for that day. No amount of scrutiny, of sounding walls or measuring dimensions brought forth the slightest suspicion, hope, or even possibility of a secret vault or crypt within the four walls. Hughes had two assistants, skilled builders both. Bannard added his efforts, but no stone or board was there that hadn't its own honest use and place. Coal bins, ash pits, wood boxes, cupboards and portable receptacles were investigated with meticulous care, and the result was absolutely nothing to bear out the theory of a crypt of any sort or size, concealed or otherwise. "And that settles that notion," summed up Hughes, as he made his report to the two interested women. "Of course, you must see, there's two ways to approach this case--one being from the question of how the murderer got in and out of that room, and the other being who the murderer was. Of course, if we find out either of those things, we're a heap forrader toward finding out the other. See?" "I see," said Miss Darrel, "but I should think you'd find it easier to work on your first question. For here's the room, the door, the lock, and all those things. But as to the murderer, he's gone!" "Clearly put, ma'am! And quite true. But the room and lock--in plain sight though they are--don't seem to be of any help. Whereas, the murderer, though he's gone, may not be able to stay gone." "Just what do you mean by that?" asked Bannard. "Two things, sir. One is, that they do say a murderer always returns to the scene of his crime." "Rubbish! I've heard that before! It doesn't mean a thing, any more than the old saw that 'murder will out' is true." "All right, sir, that's one; then, again, there's a chance that said murderer may not be able to stay away because we may catch him." "That's the talk!" said Bannard. "Now you've said something worth while. Get your man, and then find out from him how he accomplished the impossible. Or, rather, the seemingly impossible. For, since somebody did enter that room, there was a way to enter it." "It isn't the entering, you know, Mr. Bannard. Everybody was out of the living room at the time, and the intruder could have walked right in the side door of that room, and through into Mrs. Pell's sitting room. The question is, how did he get out, after ransacking the room and killing the lady, and yet leave the door locked after him." "All right, that's your problem then. But, as I said, if he _did_ do it, or _since_ he did do it, somebody ought to be able to find out how." "I'll subscribe to that, somebody _ought_ to be able to, but who is the somebody?" "Don't ask me, I'm no detective."