“This man Klein must be arrested immediately. How did you know that we had caught Yat Sen, Mrs. Gray?” he demanded, turning to the demure figure of the Overton girl.
“I heard the doctor reporting it over the telephone in the cellar. The telephone evidently leads across the river. He reports every night at about the same time. It was from overhearing him that I was able to warn you about the proposed firing of Barracks Number Two.”
“Now that the matter is in my mind, will you tell me why you had your tunic pinned to the wall?” questioned Captain Boucher.
“There is a dictaphone behind the wallpaper at that point, with an opening through the paper so small that one never would notice it.”
“I thought so. How did you chance to discover it?”
“I looked for it.”
The two officers exchanged meaning glances.
“How did you come to suspect the doctor?” continued the captain.
“He was too suave to be genuine. Then, too, I presume my intuition had something to do with it. Little things, expressions on faces, mannerisms, all these things always did make an impression on me.” Grace then went on to relate conversations that she had heard when the doctor was talking at the cellar telephone.
“The doctor in his conversation this evening referred to some person as the Babbler. Do you know whom he meant?”