“Yes. Mrs. Berlyn said she must go and see how the others were getting along. She watched us play for some time, then went to the drawing room. She came back after a few minutes to say that supper was ready.” “Now, Dr. Lancaster, just one other question. Can you tell me at what time Mrs. Berlyn went into the drawing room?” “I really don’t think I can. I wasn’t paying special attention to her movements. I should say perhaps half an hour before supper, but I couldn’t be sure.” “That’s all right,” said French. “Now if I could see Mrs. Lancaster for a moment I should be done.” Mrs. Lancaster was a dark, vivacious little woman who seemed to remember the evening in question much more clearly than did her husband. “Yes,” she said, “I was playing bridge with Miss Lucy Pym, Mr. Cowls, and Mr. Leacock. I remember Mrs. Berlyn coming in about ten. She laughed and said: ‘Oh, my children, don’t be frightened. I couldn’t think of disturbing such a serious game. I’ll go back to our snooker.’ She went away, and presently came back and called us to the library to supper.” “How long was she away, Mrs. Lancaster?” “About twenty minutes, I should think.” This seemed to French to be all that he wanted. However, he thought it wise to get the key of the Berlyns’ house and have a look at the layout. The drawing room was in front, with the library behind it, but between the two there was a passage with a side door leading into the garden. He felt satisfied as to the use to which that passage had been put on the night in question. He could picture Mrs. Berlyn fixing up the uneven number of guests, among whom would be some who played billiards and some who did not. The proposals for snooker and bridge would almost automatically follow, involving the division of the party in two rooms. Mrs. Berlyn as hostess would reasonably be the odd man out when the change was made from snooker to billiards. The result of these arrangements would be that when she slipped out to the works through the side door, each party would naturally assume she was with the other, while if any question as to this arose, her reëntry at supper-time would suggest to both that she had gone out to overlook its preparation. These discoveries justified French’s theory, but they did not prove it, and he racked his brains for some test which would definitely establish the point. At last an idea occurred to him which he thought might at least help.