"They then came straight here, and the girl followed them. Mr. and Mrs.
Jones have not been out since."

"Are you sure of that?"

"Perfectly. There is no way to get out of that house from the rear."

"How about the fire-escape?"

"There is only that one on the side which you can see. The little yard
back of the house is walled in by buildings."

"So Mr. and Mrs. Jones must be inside?"

"Yes."

"And the girl?"

"She is out. She has been going on errands half a dozen times, but
usually to the grocer's or the butcher's around the corner. I don't know
where she has gone this time. She's been out about a quarter of an
hour."

"All right. I'm going over there."

Nick changed his disguise to that in which Jones had seen him. He did it
in the hall of the flat house, while waiting for the door to be opened
in answer to his ring.