leading to the back porch of each apartment. A person could pass
from the alley up to the third floor without being noticed, even by
tenants in the building itself.

Morgan instantly noted that an automobile could stand in the
alleyway close to the entrance; that a person could come down these
stairs unobserved, step into the car and be quietly carried away,
disappearing into the general traffic of the streets in probably not
more than two minutes after leaving the apartment.

Here, thought Morgan, was a possible solution of the sudden
disappearance of the person who had been either murdered or wounded.
It was a problem, of course, as to which door they had been brought
through, and the solution of that problem would very likely bring
him pretty close to the person or persons who had participated in
the events of the night before.

Unquestionably, the rear door of the apartment where the trouble had
taken place had not been used for this purpose, although it would
seem the logical and quickest way to make an exit. On the other
hand, for that very reason, the persons back of the supposed crime
had been clever enough to avoid it, thus adding a mystifying element
to what had taken place.

In the light of present developments, two possible exits suggested
themselves to Morgan. These were the Atwood and Marsh apartments.
The girl, however, claimed that she had slept through the night, and
it hardly seemed possible that anyone could pass through her flat
without arousing her. This, of course, meant taking for granted her
story that she was alone in the apartment and had been in bed and