light drive. This
point, however, attracted no attention. Marlowe had an absolutely
air-tight alibi in his presence at Southampton by 6.30; nobody thought
of him in connection with a murder which must have been committed after
12.30--the hour at which Martin the butler had gone to bed. But it was
the Manderson who came back from the drive who went out of his way to
mention Southampton openly to two persons. He even went so far as
to ring up a hotel at Southampton and ask questions which bore out
Marlowe's story of his errand. This was the call he was busy with when
Martin was in the library.

Now let us consider the alibi. If Manderson was in the house that night,
and if he did not leave it until some time after 12.30, Marlowe could
not by any possibility have had a direct hand in the murder. It is a
question of the distance between Marlstone and Southampton. If he had
left Marlstone in the car at the hour when he is supposed to have done
so--between 10 and 10.30--with a message from Manderson, the run would
be quite an easy one to do in the time. But it would be physically
impossible for the car--a 15 h.p. four-cylinder Northumberland, an
average medium-power car--to get to Southampton by half-past six unless
it left Marlstone by midnight at latest. Motorists who will examine the
road-map and make the calculations required, as I did in Manderson's
library that day, will agree that on the facts as they appeared there
was absolutely no case against Marlowe.

But even if they were not as they appeared; if Manderson was dead by
eleven o'clock, and if at about that time Marlowe impersonated him at
White Gables; if Marlowe retired to Manderson's bedroom--how can all
this be reconciled with his appearance next morning at Southampton? He
had to get out of the house, unseen and unheard, and away in the car by
midnight. And Martin, the sharp-eared Martin, was sitting up until 12.30
in his pantry, with the door open, listening for the telephone bell.
Practically he was standing sentry over the foot of the staircase, the
only staircase leading down from the bedroom floor.

With this difficulty we arrive at the last and crucial phase of my
investigation. Having the foregoing points clearly in mind, I spent the
rest of the day before the inquest in talking to various persons and in
going over my story, testing it link by link. I could only find the one
weakness which seemed to be involved in Martin's sitting up until 12.30;
and s