s had kept him in the dark. Bentwood was to
work it. Bentwood was to administer the drug, but he gave too much. The
consequence was an overdose, as you may gather."

Field smiled peculiarly, but he gave no hint as to the extent of his own
discovery.

"These people did not want a _post mortem_," Berrington said. "They did
not desire that any traces of that practically unknown drug should be
discovered."

"And you think that they all ran that risk to guard their secret?" asked
Field. "Well, you have provided me with one or two surprises, but I am
going to provide you with as many before we go to bed. Have you
discovered anything further?"

"Oh, yes," said Berrington, "this collar, for instance. I am in a
position to prove beyond the shadow of a doubt that Sir Charles wore it
on the night of the dinner party. I found that down here in this very
vault. No further proof is wanted that the body was here. But what
puzzles me is this: we were so quickly on the spot that those rascals
had not the slightest chance of disposing of the corpse. What then has
become of it--why can't we find it? Now that one knows all about the
ruby mines and the concessions--which appear to me to be very
valuable--the mystery becomes tolerably clear. But the corpse, where is
it?"

"Are you quite sure that there is a corpse?" asked Field drily. "Let us
go and ask Bentwood."

Bentwood sat up and smiled as his two chief tormentors came back. He was
ready to afford any information that the gentlemen required.

"It is not much that I am going to ask," said Field. "Only this: Please
take us at once to the spot where we can find the body of Sir Charles
Darryll."

Bentwood jumped nimbly to his feet. The question seemed to fairly
stagger him. If he had thought of concealing anything, he abandoned the
idea now.

"Come this way, gentlemen," he said. "You are too many for me
altogether. I wish to heaven that I had kept my medical discoveries to
myself."

CHAPTER XXXVIII

Bentwood led the way from the dining-room up a back staircase, and
paused before what looked like a portion of the wallpaper. There was a
little discoloured spot about half way between the dado and the floor,
and on this the doctor pressed a shaking thumb. A part of the wall fell
away and disclosed a small room beyond. The room had evidently been
occupied lately, for there was a fire in the grate and the remains of a
meal on the table. The room itself was empty.

"Well,