"He's not coming over, is he? Pity! It would have done him a world of good. Yes, Jimmy Crocker and I have always been great pals. He's a bit of a nut, of course, . . . I beg your pardon! . . . I mean . . ." He broke off confusedly, and turned to Willie again to cover himself. "How are you getting on with the jolly old stuff?" he asked. If Willie had objected to Partridgite being called "the stuff," he was still less in favour of its being termed "the jolly old stuff." He replied coldly. "I have ceased to get along with the jolly old stuff." "Struck a snag?" enquired Lord Wisbeach sympathetically. "On the contrary, my experiments have been entirely successful. I have enough Partridgite in my laboratory to blow New York to bits!" "Willie!" exclaimed Mrs. Pett. "Why didn't you tell me before? You know I am so interested." "I only completed my work last night." He moved off with an important nod. He was tired of Lord Wisbeach's society. There was something about the young man which he did not like. He went to find more congenial company in a group by the window. Lord Wisbeach turned to his hostess. The vacuous expression had dropped from his face like a mask. A pair of keen and intelligent eyes met Mrs. Pett's. "Mrs. Pett, may I speak to you seriously?" Mrs. Pett's surprise at the alteration in the man prevented her from replying. Much as she liked Lord Wisbeach, she had never given him credit for brains, and it was a man with brains and keen ones who was looking at her now. She nodded. "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.