open the drawer and secured the papers, still
holding in his hand the instrument used for slipping back the tiny lock,
he turned to leave the room by the open window, and was suddenly
confronted by the real Sir Alan, who recognised him and guessed his object
in being present at that hour.

Brett had gone thus far in his spoken commentary on the affair as it now
presented itself to his mind when Winter asked:

"Why do you say 'recognised' him, Mr. Brett? We have no evidence that Sir
Alan had ever seen Ooma?"

"What, none? Search through your memory. Did not the stationmaster see a
third David Hume leave the station that day when the movements of only two
are known to us. What became of this third personage during the afternoon?
Where did he change into evening dress? Why did Sir Alan leave documents
of such grave importance in so insecure a hiding-place?"

"There is no use in asking me questions I can't answer," snapped the
detective.

"Perhaps not. I think you said that you amused yourself in your Middle
Street lodgings by taking to pieces a small electrical machine fitted
together by your companion?"

"Yes, sir; but what of that?"

"Let us suppose that, instead of a complex machine he built a small arch
of toy bricks, and you were well acquainted with the model whilst each
brick was numbered in rotation, don't you think you could manage to
reconstruct the arch after repeated efforts?"

"I expect so."

"Well, my dear Winter, we have now got together every material stone in
our edifice. Mrs. Capella's yielding to blackmail is the keystone of the
arch. Every loose block fits at once into its proper place. The Japanese,
Ooma, must have met Sir Alan and discussed this very question with him.
The baronet must have unwittingly revealed the family secret, and the Jap
was clever enough to perceive its value. Further, the murder was
unpremeditated, the inspiration of a desperate moment, and the weapon
selected shows a sort of fiendish mandate suggested by family feud. Ooma
is undoubtedly--"

But Smith entered, apologetic, doubtful.

"Mr. Holden is here, sir, and says he wishes to see you immediately."

Holden's news was important. Capella had left Liverpool Street half an
hour ago for Beechcroft, and in the same train travelled Ooma.

"Are you sure of this?" demanded Brett, excitedly springing from his
chair.

"Quite certain, sir. Mr. Winter's mate followed him to the station, and
told me who the Japanese was.