We have taken care of that.

As for the other houses, they provide the simplest means of access to the center one.

Doorways have been made in the cellar walls and special staircases built.
Consequently, if you broke open the door of 412 you would find the way barred by two other locked doors, while the occupants, if aroused, could escape from either or both of the next houses.

We Chinese have a long acquaintance with the needs of a secret society.

You may take it from me that the obvious way into or out of an opium den, for instance, is never the way used by the habitues." By this time the commissioner, Handyside, Furneaux and the inspector had come up, and the five formed a little group in the center of a semicircle of detectives and police.