else--some one who had eluded Miss Strong's notice--had removed the
cipher message.

Promptly he had telephoned to her to meet him. He was glad that he had
done so, for her evident perturbation as she answered the 'phone both
interested and puzzled him. Pausing just long enough to report to Chief
Fleck, he hastened to the rendezvous, arriving there first. He selected
a bench apart from the others, where the wall jutted out from the walk,
and seating himself, idled there as if merely watching the river. In
obedience with his instructions Jane, when she arrived, planted herself
nonchalantly on the same bench, and paying no attention to him,
pretended to be reading a letter.

Presently Carter rose and stretching himself lazily, as if about to
leave, turned to face the Drive, his keen eyes taking in all the
passers-by. Apparently satisfied, he sat down abruptly and turned to
speak to the girl beside him.

"All right, K-19," he said, "it's safe. Now we can talk."

"I've got such a lot to tell," cried Jane.

"First," said Carter, "just where did you put that cipher message when
you put it back?"

"What!" cried the girl, her face blanching, "wasn't it there? Didn't you
find it?"

Carter shook his head.

"It must be there," she insisted. "Are you sure you looked in the right
book--the fifth book from the end on the second shelf on the up-town
side of the store."

"It's not there. I examined every book there, on the shelves above and
below and at the other end, too."

"The clerk in the store, that girl--must have hidden it," cried Jane
with conviction.

"That's not likely. She's an English girl--from Liverpool. She has three
brothers fighting on the Allies' side. We can leave her out of it."

"Who else could have taken it?"

"There's only one answer," said Carter slowly and impressively. "Some
one went into that store between the time you copied the message and
the time I met you at the drug-store. You told me no one but a couple of
girls had entered. Was there any one else? Think--think!"

"There was no one," said Jane thoughtfully, "no one except the two girls
together. I never thought of suspecting them."

"What did they look like? Could you identify them?"

"I did not notice them particularly," Jane confessed. "I was expecting
Mr. Hoff's confederate to be a man."

"They're using a lot of women spies," asserted Carter. "Don't you
remember what the girls looked like?"

"One of them," said Jane thoughtf