"Why did he do that?" asked Drench suddenly.
"Can't you guess?" put in Vernon impatiently. "Mr. Dimsdale expected The Spider, and wished to see if he would come."
"But he didn't know what The Spider was like. No one knows."
"I daresay. But Mr. Dimsdale knew those whom his daughter had invited to the ball. If an unknown person had unmasked he would have jumped to the conclusion, and perhaps truly, that he was The Spider. Well, Miss Hest?"
"Everyone who unmasked were people we knew," she continued, "for I stood with Ida near Mr. Dimsdale, receiving the guests. At a quarter to eleven Mr. Dimsdale went to the library."
"Certainly. No one, to my knowledge, entered the library during the whole of that evening until Ida, in search of her father, insisted upon going in, notwithstanding the prohibition, at a quarter to twelve. Then she found Mr. Dimsdale seated in his chair, quite dead."
Inspector Drench arose. "Come and see the room, Mr. Vernon," he said, moving towards the door. "Nothing has been disturbed, not even the corpse. Everything remains as Miss Dimsdale found it at a quarter to twelve."
"And Ida fainted," whispered Frances in Vernon's ear as the trio crossed the hall to enter the library. "Poor child! It was no wonder, when the sight was so horrid. She's in bed now, crying her heart out. Inspector," added Miss Hest, raising her voice, "you won't want me any longer? Let me return to Miss Dimsdale, as she needs every attention."
"Very good, miss. I shall continue your examination in the morning."
"One moment," said Vernon, laying his hand on her sleeve as she moved away. "I want to know if any guest arrived after Mr. Dimsdale went into the library."
"Two. But Ida and I made them unmask. We knew them quite well. Mr. and Mrs. Horner from Finchley. And I may tell you, Mr. Vernon, that Mr. Dimsdale came out of the library at five minutes to eleven for a single moment to ask if you had arrived."
"I wish I had arrived," said Vernon bitterly, "I might have prevented this tragedy. Are you sure, Miss Hest, that no strangers were at the ball?"
"Well," she said thoughtfully, "it is difficult to say, since all were masked. But no stranger was there to my knowledge, and when the crime was discovered everyone unmasked. We knew all the guests, as we had known them when they arrived; still, some stranger might have slipped in. But I must go to Ida. I'll tell you anything else you wish to know in the morning."