“Why, you don’t think she did the shooting?” I asked, half hoping, I must admit, for an assenting nod from him.

“Well,” he answered dryly, “one shouldn’t let any preconceived hypothesis stand between him and the truth.  I’ve made a guess at the whole thing already.  It may or it may not be right.  Anyhow she will fit into it.  And if it’s not right, I’ve got to be prepared to make a new guess, that’s all.”

When we reached the laboratory on our return, the inspector’s man Riley was there, waiting impatiently for Kennedy.

“What luck?” asked Kennedy.

“I’ve got a list of purchasers of that kind of revolver,” he said.  “We have been to every sporting-goods and arms-store in the city which bought them from the factory, and I could lay my hands on pretty nearly every one of those weapons in twenty-four hours—­provided, of course, they haven’t been secreted or destroyed.”

“Pretty nearly all isn’t good enough,” said Kennedy.  “It will have to be all, unless—­”

“That name is in the list,” whispered Riley hoarsely.

“Oh, then it’s all right,” answered Kennedy, brightening up.  “Riley, I will say that you’re a wonder at using the organisation in ferreting out such things.  There’s just one more thing I want you to do.  I want a sample of the notepaper in the private desks of every one of these people.”  He handed the policeman a list of his 9 “suspects,” as he called them.  It included nearly every one mentioned in the case.

Riley studied it dubiously and scratched his chin thoughtfully.  “That’s a hard one, Mr. Kennedy, sir.  You see, it means getting into so many different houses and apartments.  Now you don’t want to do it by means of a warrant, do you, sir?  Of course not.  Well, then, how can we get in?”

“You’re a pretty good-looking chap yourself, Riley,” said Kennedy.  “I should think you could jolly a housemaid, if necessary.  Anyhow, you can get the fellow on the beat to do it—­if he isn’t already to be found in the kitchen.  Why, I see a dozen ways of getting the notepaper.”

“Oh, it’s me that’s the lady-killer, sir,” grinned Riley.  “I’m a regular Blarney stone when I’m out on a job of that sort.  Sure, I’ll have some of them for you in the morning.”

“Bring me what you get, the first thing in the morning, even if you’ve landed only a few samples,” said Kennedy, as Riley departed, straightening his tie and brushing his hat on his sleeve.

“And now, Walter, you too must excuse me to-night,” said Craig.  “I’ve got a lot to do, and sha’n’t be up to our apartment till very late—­or early.  But I feel sure I’ve got a strangle-hold on this mystery.  If I get those papers from Riley in good time to-morrow I shall invite you and several others to a grand demonstration here to-morrow night.  Don’t forget.  Keep the whole evening free.  It will be a big story.”