d not bring the window with me, I
photographed them, sticking a bit of black paper on the other side of
the glass for the purpose. The bowl comes from Manderson's room. It is
the bowl in which his false teeth were placed at night. I could bring
that away, so I did.'

'But those cannot be Mabel's finger-marks.'

'I should think not!' said Trent with decision. 'They are twice the size
of any print Mrs Manderson could make.'

'Then they must be her husband's.'

'Perhaps they are. Now shall we see if we can match them once more? I
believe we can.' Whistling faintly, and very white in the face, Trent
opened another small squat bottle containing a dense black powder.
'Lamp-black,' he explained. 'Hold a bit of paper in your hand for a
second or two, and this little chap will show you the pattern of your
fingers.' He carefully took up with a pair of tweezers one of the leaves
cut from his diary, and held it out for the other to examine. No marks
appeared on the leaf. He tilted some of the powder out upon one surface
of the paper, then, turning it over, upon the other; then shook the leaf
gently to rid it of the loose powder. He held it out to Mr Cupples in
silence. On one side of the paper appeared unmistakably, clearly printed
in black, the same two finger-prints that he had already seen on the
bowl and on the photographic plate. He took up the bowl and compared
them. Trent turned the paper over, and on the other side was a bold
black replica of the thumb-mark that was printed in grey on the glass in
his hand.

'Same man, you see,' Trent said with a short laugh. 'I felt that it must
be so, and now I know.' He walked to the window and looked out. 'Now
I know,' he repeated in a low voice, as if to himself. His tone was
bitter. Mr Cupples, understanding nothing, stared at his motionless back
for a few moments.

'I am still completely in the dark,' he ventured presently. 'I have
often heard of this fingerprint business, and wondered how the police
went to work about it. It is of extraordinary interest to me, but upon
my life I cannot see how in this case Manderson's fingerprints are
going--'

'I am very sorry, Cupples,' Trent broke in upon his meditative speech
with a swift return to the table. 'When I began this investigation I
meant to take you with me every step of the way. You mustn't think I
have any doubts about your discretion if I say now that I must hold my
tongue about the whole thing, at least for a time. I wil