ns for the afternoon. He had decided that he must enter the
Thorne mansion again that very day, for he must find out the meaning of
the red-shaded lamp. And now that the housekeeper was away it would be
easier for him to get into the house, therefore it must be done at once.
His excuse was all ready, for he had been weighing possibilities.
He dismissed his cab a block from his own home and entered his house
cautiously.

Muller's lodgings consisted of two large rooms, really much too large
for a lone man who was at home so little. But Muller had engaged them
at first sight, for the apartment possessed one qualification which was
absolutely necessary for him. Its situation and the arrangement of its
doors made it possible for him to enter and leave his rooms without
being seen either by his own landlady or by the other lodgers in the
house. The little apartment was on the ground floor, and Muller's own
rooms had a separate entrance opening on to the main corridor almost
immediately behind the door. Nine times out of ten, he could come and go
without being seen by any one in the house. To-day was the first
time, however, that Muller had had occasion to try this particular
qualification of his new lodgings.

He opened the street door and slipped into his own room without having
seen or been seen by any one.

Fifteen minutes later he left the apartment again, but left it such a
changed man that nobody who had seen him go in would have recognised
him. Before he came out, however, he looked about carefully to see
whether there was any one in sight He came out unseen and was just
closing the main door behind him, when he met the janitress.

"Were you looking for anybody in the house?" said the woman, glancing
sharply at the stranger, who answered in a slightly veiled voice: "No,
I made a mistake in the number. The place I am looking for is two houses
further down."

He walked down the street and the woman looked after him until she saw
him turn into the doorway of the second house. Then she went into her
own rooms. The house Muller entered happened to be a corner house with
an entrance on the other street, through which the detective passed
and went on his way. He was quite satisfied with the security of his
disguise, for the woman who knew him well had not recognised him at all.
If his own janitress did not know him, the people in the Thorne house
would never imagine it was he.

And indeed Muller was entirely changed. I