"Leave Cæsar here while you go for what you need. Down, Cæsar! Garde!"
The dog growled and went on guard forthwith.
"Now, we'll have a look inside."
The alleyway door stood open and, using his lantern with the utmost care, Coquenil went first, mounting the stairs slowly, followed by Gritz. At the top they came to a narrow landing and a closed door.
"This opens directly into Number Seven?" asked the detective.
"Yes."
"Is it usually locked or unlocked?"
"IT is always locked."
"Well, it's unlocked now," observed Coquenil, trying the knob. Then, flashing his lantern forward, he threw the door wide open. The room was empty.
"Let me turn up the electrics," said the proprietor, and he did so, showing furnishings like those in Number Six except that here the prevailing tint was pale blue while there it was pale yellow.