The men had trooped towards the conservatory, but the Professor met them on the portals.
[Illustration: "CONFESS THY SINS, MY GOOD MAN."] [Illustration: THE BLACK BOX IS INTRODUCED INTO THE STORY.] "I suggest," he said courteously, "that we leave the conservatory exactly as it is until the arrival of Mr.Sanford Quest.

It will doubtless aid him in his investigations if nothing is disturbed.

All the remaining doors are locked, so that no one can escape if by any chance they should be hiding." They all agreed without dissent, and there was a general movement towards the buffet to pass the time until the coming of Mr.Sanford Quest.

The Professor met the great criminologist and his assistant in the hall upon their arrival.

He took the former at once by the arm.
"Mr.Quest," he began, "in a sense I must apologise for my peremptory message.