With a word of excuse to Lady Tamplin； he broke it open； and an expression of utter astonishment came over his face as he read； then he looked at his hostess。
〃This is most extraordinary。 I say； Rosalie； I am afraid I will have to leave you。 The Prefect of Police wants to see me at once。 I can't think what about。〃
〃Your sins have found you out；〃 remarked Lenox。
〃They must have；〃 said Derek； 〃probably some idiotic nonsense； but I suppose I shall have to push off to the Prefecture。 How dare the old boy rout me out from dinner？ It ought to be something deadly serious to justify that；〃 and he laughed as he pushed back his chair and rose to leave the room。
Chapter 13
VAN ALDIN GETS A TELEGRAM
On the afternoon of the 15th February a thick yellow fog had settled down on London。
Rufus Van Aldin was in his suite at the Savoy and was making the most of the atmospheric conditions by working double time。 Knighton was overjoyed。 He had found it difficult of late to get his employer to concentrate on the matters in hand。 When he had ventured to urge certain courses； Van Aldin had put him off with a curt word。 But now Van Aldin seemed to be throwing himself into work with redoubled energy； and the secretary made the most of his opportunities。 Always tactful； he plied the spur so unobtrusively that Van Aldin never suspected it。
Yet in the middle of this absorption in business matters； one little fact lay at the back of Van Aldin's m