owledge of the man. He was
supposed to have been an American sailor. Once or twice he has been
visited on the boat by a couple of men who pulled up in a dinghy hired
from Blackfriars. The regular waterman hardly ever caught a glimpse of
him--he never showed himself by day. This morning a letter was sent
aboard addressed to James Floyd, Esq. I never opened it, thinking
perhaps you might prefer to do so. We searched the barge from end to
end, and Jones is outside with a bag of different things you might like
to see. What I thought most important, however, was this."

He dipped his hand in his jacket pocket and, withdrawing a small package
wrapped in newspaper, carefully unfolded it. Something fell with a
tinkle on Foyle's desk.

"By the living jingo!" ejaculated Green. "It's the sheath of the
dagger!"

The superintendent picked up the thing--a small sheath of bright steel
with, on the outside, a screw manipulating a catch by which it might be
fastened to a belt. He handled it delicately from the ends.

"I believe you're right," he said. "Now, what about the letter?"

CHAPTER XXXVI

The motive of the actions taken that day by Eileen Meredith had been
accurately diagnosed by Heldon Foyle. She had returned to her home after
her visit to the police at Waterloo Bridge in a state of the keenest
uncertainty. Not for an instant did she credit the paragraph referring
to the dead body. The police had been able to read the cipher message
from Grell, and she assumed correctly enough that they had been more
successful than herself in obtaining an early glimpse of the
advertisement. What, then, had become of her note of warning?

She was half reclining in a big easy-chair, her arms resting on the
broad ledges, her fists tightly clenched. Her train of thought led her
to alarming conclusions. If the police had been watching--and that now
occurred to her as having been an obvious step--they must not only have
seen her note, but they might have secured and questioned the person who
brought the advertisement. And if so, might not Robert Grell's
hiding-place have been betrayed? Her heartbeats became unsteady. What if
the visit of the detectives down the river had been not to identify a
drowned corpse, but a living prisoner? Suppose Grell were already in
their hands?

She jumped to her feet. The watch on her wrist spoke to quarter to
eleven. Her reflections had occupied many hours. She was already dressed
in a brown walking