over the watch, and Allerdyke, opening the case,
delicately removed the print. He sat down at the table with his back to
the light, and carefully examined the thing back and front, while the
detective, glass in hand, cigar in lips, and thumb in the armhole of his
waistcoat, watched him appreciatively and inquisitively.

"Make aught new out of it, sir?" he asked after a while.

Instead of answering, Allerdyke laid the photograph down, went across to
another table, and took from it his album. He turned its leaves over
until he came to a few loose prints. He picked them up one after another
and examined them. And suddenly he knew the secret. There was no longer
any problem, any difficulty about that photograph. He knew--now! And with
a sharp exclamation, he flung the album back to the side-table, and
turned to the detective.

"Chettle!" he said. "You know me well enough to know that I can make it
well worth any man's while to keep a secret until I tell him he can speak
about it! What!"

"I should think so, Mr. Allerdyke," responded Chettle, readily enough.
"And if you want me to keep a secret--"

"I do--for the time being," answered Allerdyke. He sat down again and
picked up the photograph which had exercised his thoughts so intensely.
"I've found out the truth concerning this," he said, tapping it with his
finger. "Yes, I've hit it! Listen, now--I told you I'd only made four
prints of this photo, and that I knew exactly where they all were--one in
my own album there, two given by James to friends in Bradford, one--as we
more recently found out--given by James to Mrs. Marlow. That one--the
Mrs. Marlow one--we believed to be--this--this!"

"And isn't it, Mr. Allerdyke?" asked Chettle wonderingly.

Allerdyke laughed--a laugh of relief and satisfaction.

"Less than an hour ago," he replied, "in fact, just before you came in,
Mrs. Marlow showed me the photo which James gave her--showed it to me,
out below there in the hall. No mistaking it! And so--when you came, I
was racking my brains to rags trying to settle what this
photo--this!--was. And now I know what it is--and damn me if I know
whether the discovery makes things plainer or more mixed up! But--I know
what this is, anyway."

"And--what is it, sir?" asked Chettle eagerly, eyeing the photo as if it
were some fearful living curiosity. "What, Mr. Allerdyke?"

"Why, it's a photograph of my photograph!" almost shouted Allerdyke, with
a thump of his big hand on the