“Averti que l’Allemagne a engage un officier a deceler la formule secrete des Etats-Unis employee a collodonnier la fulmi-coton pour la poudre sans fumeee a l’artillerie de gros calibre; et que Madeline Spencer, emissaire de l’Allemagne a Paris,—­photographie ci, incluse—­a ete de chargee la recevoir.  Ne se peut decouvrir le nom du traitre.  Spencer est partie pour New York sur la Lusitania qui doit arriver le quatorze.  A toute force interceptez la formule; ou empechez a moins que l’Allemagne ne l’obtienne.  Spencer pas importante a la France.”

And under it he wrote the English translation:  “Informed Germany has induced an officer to betray United States secret formula for colloding process of treating gun-cotton for smokeless powder for high power guns, and that Madeline Spencer, a German Secret agent in Paris, photograph enclosed herein, is delegated to receive same.  Cannot ascertain name of traitor.  Spencer sailed Lusitania, due New York, fourteenth.  Take any means to intercept formula; or at least to prevent Germany obtaining it.  Spencer not essential to France.”

Spencer not essential to France! Surely this woman had great power, either of knowledge or of friends; she resided in Paris, yet France was reluctant to lift hand against her so long as she was on French soil.  Well, he would turn the matter over to Harleston; let him decide whether it was to be thumbs up or thumbs down for her Alluringness.  Furthermore, the meeting with Snodgrass now assumed much significance.  Snodgrass was an ex-army officer.  Harleston must be warned at once.

He tried for him at the Collingwood, the Cosmopolitan, the Rataplan, and finally at the Chateau.  He got him there.

“Can you come here at once?” he asked.

“Not well,” said Harleston, “I’ve an appointment.”

“Forget it!” Carpenter exclaimed.  “I’ve found the key-word and made the translation.  It’s serious—­Very well, come right in; I’ll be waiting.”

Harleston scribbled a note to Mrs. Clephane and sent it up by a page; he would be back in half an hour; would she meet him in the Alley.

XXII

THE RATAPLAN

A moment before Harleston’s return, Madeline Spencer, stepping out of the F Street elevator, was met by Snodgrass who had been walking up and down the lobby.  They took a taxi and sped away; followed closely by another taxi, which their driver was most careful not to distance.  A second later Harleston entered the corridor.  As he was about to greet Mrs. Clephane, a man approached him and said: 

“They have started, sir; Burke’s just behind in a taxi—­and both drivers are wise.  They’re bound for the Rataplan.”

“Follow them and wait just outside,” Harleston ordered—­and turned to Mrs. Clephane.  “I must go to the Rataplan at once,” said he.  “Let us lunch there.  The end of the affair of the cab of the sleeping horse is in sight; I thought you might like to see it.”