"Shall you bring them upstairs, sir?" inquired Polton, with an alarmed
expression.

"I expect I shall have to," answered Thorndyke.

"Then I shall just smarten the laboratory up a bit," said Polton, who
evidently appreciated the difference between the masculine and feminine
view as to the proper appearance of working premises.

"And so Miss Gibson wanted to know our private views on the case?" said
Thorndyke, when his voracity had become somewhat appeased.

"Yes," I answered; and then I repeated our conversation as nearly as I
could remember it.

"Your answer was very discreet and diplomatic," Thorndyke remarked, "and
it was very necessary that it should be, for it is essential that we
show the backs of our cards to Scotland Yard; and if to Scotland Yard,
then to the whole world. We know what their trump card is and can
arrange our play accordingly, so long as we do not show our hand."

"You speak of the police as your antagonists; I noticed that at the
'Yard' this morning, and was surprised to find that they accepted the
position. But surely their business is to discover the actual offender,
not to fix the crime on some particular person."

"That would seem to be so," replied Thorndyke, "but in practice it is
otherwise. When the police have made an arrest they work for a
conviction. If the man is innocent, that is his business, not theirs; it
is for him to prove it. The system is a pernicious one--especially since