'I keep that by me as a sort of morbid memento.
It is the key to the lock I smashed. I might have saved myself the
trouble, if I had known that this key was at that moment in the
left-hand side-pocket of my overcoat. Manderson must have slipped it in,
either while the coat was hanging in the hall or while he sat at my side
in the car. I might not have found the tiny thing there for weeks: as
a matter of fact I did find it two days after Manderson was dead, but
a police search would have found it in five minutes. And then I--I
with the case and its contents in my pocket, my false name and my sham
spectacles and the rest of it--I should have had no explanation to offer
but the highly convincing one that I didn't know the key was there.'

Trent dangled the key by its tape idly. Then: 'How do you know this is
the key of that case?' he asked quickly.

'I tried it. As soon as I found it I went up and fitted it to the lock.
I knew where I had left the thing. So do you, I think, Mr Trent. Don't
you?' There was a faint shade of mockery in Marlowe's voice.

'Touche,' Trent said, with a dry smile. 'I found a large empty
letter-case with a burst lock lying with other odds and ends on the
dressing-table in Manderson's room. Your statement is that you put it
there. I could make nothing of it.' He closed his lips.

'There was no reason for hiding it,' said Marlowe. 'But to get back to
my story. I burst the lock of the strap. I opened the case before one
of the lamps of the car. The first thing I found in it I ought to have
expected, of course, but I hadn't.' He paused and glanced at Trent.

'It was--' began Trent mechanically, and then stopped himself. 'Try
not to bring me in any more, if you don't mind,' he said, meeting the
other's eye. 'I have complimented you already in that document on your
cleverness. You need not prove it by making the judge help you out with
your evidence.'

'All right,' agreed Marlowe. 'I couldn't resist just that much. If you
had been in my place you would have known before I did that Manderson's
little pocket-case was there. As soon as I saw it, of course, I
remembered his not having had it about him when I asked for money, and
his surprising anger. He had made a false step. He had already fastened
his note-case up with the rest of what was to figure as my plunder, and
placed it in my hands. I opened it. It contained a few notes as usual, I
didn't count them.

'Tucked into the flaps of the big case