Experience and observation of life had taught Marshall Allerdyke that good counsel is one of life’s most valuable assets.  He could think for himself and decide for himself at any moment, but he knew the worth and value of putting two heads together, especially at a juncture like this.  And so, the afternoon being still young, he went off to his warehouse in Gresham Street, closeted himself with Ambler Appleyard, and having pledged him to secrecy, told him all that had happened since the previous morning.

Ambler Appleyard listened in silence.  It was only two or three hours since he had listened to another story—­the report of the two Gaffneys, and Allerdyke, all unaware of that business, had come upon him while he was still thinking it over.  And while Appleyard gave full attention to all that his employer said, he was also thinking of what he himself could tell.  By the time that Allerdyke had finished he, too, had decided to speak.

“So there it is, my lad!” exclaimed Allerdyke, throwing out his hands with an eloquent gesture as he made an end of his story.  “I hope I’ve put it clearly to you.  It’s just as that Chap Chettle said—­the whole secret is in that photograph!  And isn’t it plain?—­that photograph must have been transferred somehow by this Mrs. Marlow to this Lydenberg.  How?  Why?  When we can answer those questions—­”

He paused at that, and, looking fixedly at his manager, shook his head half-threateningly.

“I’ll tell you what it is, Ambler,” he went on, after a moment’s silence.  “I’ve got a good, strong mind to go straight to the police authorities, tell ’em what I know, insist on ’em fetching Chettle up from Hull at once, and having that woman arrested.  Why not?”

“No!” said Appleyard firmly.  “Not yet.  Too soon, Mr. Allerdyke—­wait a bit.  And now listen to me—­I’ve something to tell you.  I’ve been busy while you’ve been away—­in this affair.  Bit of detective work.  I’ll tell you all about it—­all!  You remember that day I went to lunch with you at the City Carlton, and you pointed out this Mrs. Marlow to me, going into Rothschild’s?  Yes, well—­I recognized her.”

“You did!” exclaimed Allerdyke.  “Nay!”

“I recognized her,” repeated Appleyard.  “I said naught to you at the time, but I knew her well enough.  As a matter of fact, I’ve known her for two years.  She lives at the same boarding-house, the Pompadour Private Hotel, in Bayswater, that I live in.  I see her—­have been seeing her for two years—­every day, morning and night.  But I know her as Miss Slade.”

“Miss?” ejaculated Allerdyke.

“Miss—­Miss Slade,” answered Appleyard.  He drew his chair nearer to Allerdyke’s, and went on in a lower voice.  “Now, then, pay attention, and I’ll tell you all about it, and what I’ve done since I got your note yesterday morning.”

He told Allerdyke the whole story of his endeavour to find out something about Rayner merely because Rayner seemed to be in Miss Slade’s confidence, and because Miss Slade was certainly a woman of mystery.  And Allerdyke listened as quietly and attentively as Appleyard had listened to him, nodding his head at all the important points, and in the end he slapped his manager’s shoulder with an approving hand.