O’Connor shook his head.  “I’d better keep out of it.  They know me too well.  Go alone.  I’ll get that stool-pigeon—­the Gay Cat is his name—­to go with you.  I’ll help you in any way.  I’ll have any number of plain-clothes men you want ready to raid the place the moment you get the evidence.  But you’ll never get any evidence if they know I’m in the neighbourhood.”

The next morning Craig scarcely ate any breakfast himself and made me bolt my food most unceremoniously.  We were out in Montclair again before the commuters had started to go to New York, and that in spite of the fact that we had stopped at his laboratory on the way and had got a package which he carried carefully.

Kennedy instituted a most thorough search of the house from cellar to attic in daylight.  What he expected to find, I did not know, but I am quite sure nothing escaped him.

“Now, Walter,” he said after he had ransacked the house, “there remains just one place.  Here is this little wall safe in Mrs. Branford’s room.  We must open it.”

For an hour if not longer he worked over the combination, listening to the fall of the tumblers in the lock.  It was a simple little thing and one of the old-timers in the industry would no doubt have opened it in short order.  The perspiration stood out on his forehead, so intent was he in working the thing.  At last it yielded.  Except for some of the family silver, the safe was empty.

Carefully noting how the light shone on the wall safe, Craig unwrapped the package he had brought and disclosed a camera.  He placed it on a writing-desk opposite the safe, in such a way that it was not at all conspicuous, and focused it on the safe.

“This is a camera with a newly-invented between-lens shutter of great illumination and efficiency,” he explained.  “It has always been practically impossible to get such pictures, but this new shutter has so much greater speed than anything ever invented before that it is possible to use it in detective work.  I’ll just run these fine wires like a burglar alarm, only instead of having an alarm I’ll attach them to the camera so that we can get a picture.  I’ve proved its speed up to one two-thousandth of a second.  It may or it may not work.  If it does we’ll catch somebody, right in the act.”

About noon we went down to Liberty Street, home of burglary insurance.  I don’t think Blake liked it very much because Kennedy insisted on playing the lone hand, but he said nothing, for it was part of the agreement.  Maloney seemed rather glad than otherwise.  He had been combing out some tangled clues of his own about Mrs. Branford.  Still, Kennedy smoothed things over by complimenting the detective on his activity, and indeed he had shown remarkable ability in the first place in locating Mrs. Branford.