arch-communist often enough to be a marked woman.

Urged by Carnes, Bolton, the head of the Secret Service, put a dozen
of his best men on her trail, but they found nothing. She had
disappeared as thoroughly as if the earth had opened and swallowed her
up. At last, as the combing of the Aberdeen marshes yielded no
results, Dr. Bird acceded to Carnes' request, and the detective left
for Washington to take personal charge of the search. Dr. Bird sat
alone in his quarters at the Officers' Club, futilely wracking his
brains for a clue to his further procedure.

The telephone rang loudly. With a grunt, he took down the receiver.

A feminine voice spoke with a strong foreign accent.

"I vant der Herr Doktor Vogel, plees!"

"You want who? Oh, yes. Vogel--bird! This is Dr. Bird speaking."

The voice instantly lost both its foreign accent and its guttural
quality.

"I thought so when you spoke, Doctor, but I wanted to make sure. This
is Thelma Andrews."

"Where the devil have you been? Half the Secret Service is looking for
you, including Carnes, who deserted me and is in Washington."

* * * * *

"He is? I'm sorry. Listen, Doctor, it's a long story and I can't go
into details now. I got a clue on the day you left. As I couldn't get
in touch with you, I followed it myself. I've located Saranoff's main
base in the Bush River marshes."

"You have! Where is it?"

"It's underground and you've passed over it a dozen times during the
past week. It's unoccupied now and the machines are idle until your
search is over. I know the way to it. If you'll join me now, we can
get in and hopelessly wreck the device in a short time. To-morrow you
can bring your men down here and take charge of it."

Dr. Bird's eyes glistened.

"I'll come at once, Thelma!" he cried. "Where are you?"

"I'm down on Romney Creek. Come down to the Water Impact Range below
Michaelville, and I'll meet you at the wharf. You'd better come alone,
because we'll have to sneak."

"Good for you!" cried the doctor. "I'll be down in an hour."

"All right, Doctor. I'll be waiting for you."

At Michaelville, Dr. Bird left his car and stepped on the scooter
which ran on the narrow gauge track connecting the range house with
the wharf on Romney Creek. He started it with no difficulty and it
coughed away into the night. For three and a half miles, nothing broke
the monotony of the trip. Dr. Bird, his hand on the throttle, kept his