"I don't see how that is to be managed, unless you break in the
door. I always hear him unlock it as I go down the stair after I
leave the tray."

"He has to take the tray in. Surely we could conceal ourselves
and see him do it."

The landlady thought for a moment.

"Well, sir, there's the box-room opposite. I could arrange a
looking-glass, maybe, and if you were behind the door--"

"Excellent!" said Holmes. "When does he lunch?"

"About one, sir."

"Then Dr. Watson and I will come round in time. For the present,
Mrs. Warren, good-bye."

At half-past twelve we found ourselves upon the steps of Mrs.
Warren's house--a high, thin, yellow-brick edifice in Great Orme
Street, a narrow thoroughfare at the northeast side of the
British Museum. Standing as it does near the corner of the
street, it commands a view down Howe Street, with its ore
pretentious houses. Holmes pointed with a chuckle to one of
these, a row of residential flats, which projected so that they
could not fail to catch the eye.

"See, Watson!" said he. "'High red house with stone facings.'
There is the signal station all right. We know the place, and we