“If your nephew has really succeeded in his experiments, you should be awfully careful.  That stuff ought not to lie about in his laboratory, though no doubt he has hidden it as carefully as possible.  It ought to be in a safe somewhere.  In that safe in your library.  News of this kind moves like lightning.  At this very moment, there may be people watching for a chance of getting at the stuff.”

Every nerve in Mrs. Pett’s body, every cell of a brain which had for years been absorbing and giving out sensational fiction, quivered irrepressibly at these words, spoken in a low, tense voice which gave them additional emphasis.  Never had she misjudged a man as she had misjudged Lord Wisbeach.

“Spies?” she quavered.

“They wouldn’t call themselves that,” said Lord Wisbeach.  “Secret Service agents.  Every country has its men whose only duty it is to handle this sort of work.”

“They would try to steal Willie’s—?” Mrs. Pett’s voice failed.

“They would not look on it as stealing.  Their motives would be patriotic.  I tell you, Mrs. Pett, I have heard stories from friends of mine in the English Secret Service which would amaze you.  Perfectly straight men in private life, but absolutely unscrupulous when at work.  They stick at nothing—­nothing.  If I were you, I should suspect every one, especially every stranger.”  He smiled engagingly.  “You are thinking that that is odd advice from one who is practically a stranger like myself.  Never mind.  Suspect me, too, if you like.  Be on the safe side.”

“I would not dream of doing such a thing, Lord Wisbeach,” said Mrs. Pett horrified.  “I trust you implicitly.  Even supposing such a thing were possible, would you have warned me like this, if you had been—?”

“That’s true,” said Lord Wisbeach.  “I never thought of that.  Well, let me say, suspect everybody but me.”  He stopped abruptly.  “Mrs. Pett,” he whispered, “don’t look round for a moment.  Wait.”  The words were almost inaudible.  “Who is that man behind you?  He has been listening to us.  Turn slowly.”

With elaborate carelessness, Mrs. Pett turned her head.  At first she thought her companion must have alluded to one of a small group of young men who, very improperly in such surroundings, were discussing with raised voices the prospects of the clubs competing for the National League Baseball Pennant.  Then, extending the sweep of her gaze, she saw that she had been mistaken.  Midway between her and this group stood a single figure, the figure of a stout man in a swallow-tail suit, who bore before him a tray with cups on it.  As she turned, this man caught her eye, gave a guilty start, and hurried across the room.

“You saw?” said Lord Wisbeach.  “He was listening.  Who is that man?  Your butler apparently.  What do you know of him?”

“He is my new butler.  His name is Skinner.”

“Ah, your new butler?  He hasn’t been with you long, then?”