Cleek plucked the letter from his extended hand, glanced at it, and puckered up his lips; then, with a gesture, he sent Dollops back below stairs, and, returning to the room, closed the door behind him.

“The enemy evidently knows all Lady Chepstow’s movements, Mr. Narkom,” he said.  “I expect she and Miss Lorne have been under surveillance all day and have been followed here.  Look at that!” He flung the letter down on a table as he spoke, and Narkom, glancing at it, saw printed in rude, illiterate letters upon the envelope the one word “Cleek.”  The identity of “Captain Burbage” was known to someone, and the secret of the house in Clarges Street was a secret no longer!

“Purposely disguised, you see.  No one, not even a little child, would make such a botch of copying the alphabet as that,” Cleek said, as he took the letter up and opened it.  The sheet it contained was lettered in the same uncouth manner, and bore these words: 

“Cleek, take a fool’s advice and don’t accept the Chepstow case.  Be warned.  If you interfere, somebody you care about will pay the price.  You’ll find it more satisfactory to buy a wedding bouquet than a funeral wreath!”

“Oh!” shuddered the two ladies in one breath.  “How horrible!  How cowardly!” And then, feeling that her last hope had gone, Lady Chepstow broke into a fit of violent weeping and laid her head on Ailsa’s shoulder.

“Oh, my baby!  My darling baby boy!” she sobbed.  “And now they are threatening somebody that you, too, love.  Of course, Mr. Cleek, I can’t expect you to risk the sacrifice of your own dear ones for the sake of me and mine, and so—­and so—­Oh, take me away, Miss Lorne!  Let me go back to my baby and have him while I may.”

“Good-night, Mr. Cleek!” said Ailsa, stretching out a shaking hand to him.  “Thank you so much for—­for what you would have done but for this.  And you were our last hope, too!”

“Why give it up then, Miss Lorne?” he said, holding her hand and looking into her eyes.  “Why not go on letting me be your last hope—­your only hope?”

“Yes, but they—­they spoke of a funeral wreath.”

“And they also spoke of a wedding bouquet!  I am going to take the case, Miss Lorne—­take it, and solve it, as I’m a living man.  Thank you!” as her brimming eyes uplifted in deep thankfulness and her shaking hand returned the pressure of his.  “Now, just give me five minutes’ time in the next room—­it’s my laboratory, Lady Chepstow—­and I’ll tell you whether I shall begin with Captain Hawksley or eliminate him from the case entirely.  You might go in ahead, Mr. Narkom, and get the acid bath and the powder ready for me.  We’ll see what the finger-prints of our gentle correspondent have to tell, and, if they are not in the records of Scotland Yard or down in my own private little book, we’ll get a sample of Captain Hawksley’s in the morning.”

Then, excusing himself to the ladies, he passed into the inner room in company with Narkom, and carried the letter with him.  When he returned it was still in his hand, but there were greyish smudges all over it.