“I want to see it!” Mrs. Clephane exclaimed.  “Have you found the key-word?”

“Carpenter found it—­I’ll tell you about it on the way out.  Come along, little lady.”

* * * * *

“But why do you suspect Captain Snodgrass?” she inquired, when Harleston had finished his account.  “He would not have access to the formula, would he?”

“The man that has access to such secrets never is the man who actually delivers,” he explained; “he has a confederate.  Snodgrass is the confederate, we think.”

“Is this secret colloding process of gun-cotton so tremendously valuable?” she asked.

“It’s a secret for which any nation would give millions of dollars.  It’s admittedly the most powerful explosive ever discovered, as well as the easiest handled.  Temperature, weather, ordinary shock have absolutely no effect on it; in fire it simply chars and doesn’t explode.  Yet when it is exploded by the proper method, lyddite, dynamite, and all the other ites, are as a gentle zephyr in comparison.  Now tell me about last night; where were you?”

“After you left,” she explained, “I wrote some letters, and then went into the corridor to drop them in the chute beside the elevator shaft; as I approached, the car came down with Mrs. Spencer in it.  Something impelled me to follow her; and running back I grabbed a cloak, and dashed for the elevator, catching it on the fly.  She wasn’t in the main corridor; on a chance, I hurried to the F Street entrance; I got there just as she stepped into a taxi and shot away.  Instantly I called another taxi and told the driver to follow the car that had just departed.  He did for a little way; but in a sudden halt of traffic at Vermont Avenue and H Street, where, you may remember, the street is torn up, we lost the other taxi; and though we drove around the north-west section for more than an hour on the chance that we’d come up with it—­my driver knew the other driver—­we never did come up with it.  But as we rolled up to the Chateau, Mrs. Spencer was alighting from a limousine with a tall, fine-looking, fair-haired chap who had the walk of a military man.”

“Snodgrass,” Harleston observed.

“She saw me; and, with a maliciously charming smile, nodded and went on.  In the corridor I came on some friends and we talked awhile.  Then I went up to my apartment, got your message, and telephoned to you.”

“Don’t do it again,” he cautioned.  “It was very dangerous.”

They turned in at the Rataplan and drew up at the carriage entrance.  Harleston helped Mrs. Clephane from the taxi and they passed into the Club-House.

He inquired of the doorman whether Mr. Carpenter was in, and another servant, who overheard the question, added that Mr. Carpenter was in the dining-room.  Harleston and Mrs. Clephane went directly in and to a table next to Carpenter’s.  Three tables away were Madeline Spencer and Snodgrass.