There must be no noise, no violence.

On each side of the Villa Rose there are other villas; a few yards away the road runs past.

A scream, a cry, the noise of a struggle--these sounds, or any one of them, might be fatal to success.
Thus the crime was planned; and there WAS no scream, there WAS no struggle.

Not a chair was broken, and only a chair upset.

Yes, there were brains behind that murder.