uable?" 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.

Harleston nodded to Mrs. Spencer and to Snodgrass, then spoke to
Carpenter and invited him over.

"I don't know if you will remember me, Mrs. Clephane," said Carpenter,
co