“And what is the business?” he continued.

“I’m not informed—­further than that it’s a secret agreement between England and Germany, which France suspects and would give much to block or to be advised of.  As to what the agreement embodies, I am in the dark—­though I fancy it has to do with some phase of the Balkan question.”

“Why would England and Germany conclude an agreement as to the Balkan question—­or any question, indeed—­in Washington?” Harleston asked.

“I do not know; I’m quite ready to admit its seeming improbability.  Possibly Germany desired the experience of her new Ambassador, Baron Kurtz, and didn’t care to order him to Europe.  Possibly, too, they chose Washington in order to avoid the spying eyes of the secret service of the other Powers.  At all events, I’ve told you all that I know.”

“Why are you here?” he went on.

“I’m here to watch—­and to do as I’m directed.  I’m on staff duty, so to speak.  I’m not quite in your class, Guy.  I’ve never operated quite alone.”  She looked at him thoughtfully.  “We two together would make a great pair—­oh, a very great pair!”

“I’m sure of it,” he replied.  “Sometime, I hope, we can try it.”

“Why not try it now?” she said gently.

“I’m in the American secret service—­and, you said, America is not involved.”

“Join with Germany—­and me—­for this once.”

He shook his head.  “I serve my country for my pleasure.  Germany is another matter.  If, sometime, in an affair entirely personal to you, Madeline, I should be able to assist you, I shall be only too glad for the chance.”

“You don’t trust me,” she replied sadly.

“Trust is a word unknown in the diplomatic vocabulary!” he smiled.  “Moreover, I couldn’t do what you want even if I believed and trusted your every word.  You want the letter—­the Clephane letter.  I haven’t it—­as you know.  It’s in the possession of the State Department.”

“Then let it remain there!” she exclaimed.

“It probably will until it’s translated,” he replied.

“It’s in cipher?”

Harleston nodded.  “Do you know what it contains?” he asked.

“Unfortunately, I don’t.”

“You would like to know?”

“Above everything!”

“And until then you would not have the French Ambassador advised of the letter, nor of the adventure of the cab?”

“Precisely, old friend, precisely.”

“How will you prevent Mrs. Clephane telling it?”

“We must try to provide for that!” she smiled.

“Why didn’t you keep her prisoner, when you had her last night?”

“That was a serious blunder; it won’t happen again.”

“H-u-m,” reflected Harleston; and his glance sought Mrs. Spencer’s and held it.  “Where is Mrs. Clephane now?” he demanded.

For just an instant her eyes narrowed and grew very dark.  Then suddenly she laughed—­lightly, with just a suggestion of mockery in the tones.