"Perhaps you will let me hear your guess," said Drench sceptically.
"The Spider, I fancy, stole in quietly through the French window, which was open, and came suddenly upon Dimsdale seated at his desk waiting to keep the appointment. Before the old man could turn The Spider had the handkerchief or cord round his neck and quietly choked him. There would be no noise and no struggle. Then he looked for the money"--Vernon pointed to the desk, several drawers of which were pulled open--"but not finding any he stole out again through the window."
"The guests in the garden would have seen him leave the room."
"What if they did? No one anticipated a crime, and no one but Miss Hest and Miss Dimsdale knew that the library was forbidden territory. Moreover, The Spider may have chosen his time to escape when another dance was in progress, the chances being that everyone would return to the ballroom. And you may be sure," added Vernon with emphasis, "that The Spider made use both of mask and domino, so that he might be taken for a guest, and might escape notice."
"But Miss Hest said that everyone unmasked----"
"Who entered the house as a guest," followed on Vernon quickly; "just so, Mr. Inspector. But The Spider entered as a stranger by the window, not wishing, perhaps, to take any chances. And, of course, we are agreed that he is infernally clever, and well posted in necessary details."
"I'm with you there," murmured Drench mournfully, "but it's a pity you and Mr. Dimsdale did not warn me of your trap. I should have caught the man easier than you amateurs."
"I am not an amateur," said Vernon unexpectedly; then, when the Inspector looked at him interrogatively, he added, "I trade as Nemo, of Covent Garden."
"Ah, yes; I've heard of you," replied Drench in a less supercilious tone. "So you are Nemo, are you, Mr. Vernon? I was told that you had solved several mysteries. In fact, a friend of mine at the Yard said you'd a head on your shoulders."
"I'll need it," said Vernon with a shrug, "to unravel this mystery."