"I didn't notice a light anywhere till I reached 219."

"Good again. And you could only find 219 by the light over the door.
Naturally you were not interested in and would not have noticed any other
number. Well, here is 218, where I propose to enter, and for which
purpose I have the keys. Come along."

David followed wonderingly. The houses in Brunswick Square are somewhat
irregular in point of architecture, and Nos. 218 and 219 were the only
matched pair thereabouts. Signs were not wanting, as Bell pointed out,
that at one time the houses had been occupied as one residence. The two
entrance-halls were back to back, so to speak, and what had obviously
been a doorway leading from one to the other had been plastered up within
comparatively recent memory.

The grim and dusty desolation of an empty house seemed to be supplemented
here by a deeper desolation. Not that there was any dust on the ground
floor, which seemed a singular thing seeing that elsewhere the boards
were powdered with it, and festoons of brown cobwebs hung everywhere.
Bell smiled approvingly as David Steel pointed the fact out to him.

"Do you note another singular point?" the former asked.

"No," David said, thoughtfully; "I--stop! The two side-shutters in the
bay-windows are closed, and there is the same vivid crimson blind in the
centre window. And the self colour of the walls is exactly the same. The
faint discoloration by the fireplace is a perfect facsimile."

"In fact, _this_ is the room you were in the other night," Bell
said, quietly.