as a momentous one. Rivero sat amazed when I
described my chance meeting with Gaston Suzor, and the clever manner
in which I had been inveigled into De Gex's house in Stretton Street.
Indeed, on comparing Gabrielle's story with my own, I now saw that at
the time I entered the house both she and the girl Engledue were in
their normal health. The coffee had not then been served though Moroni
had gone out of the room, no doubt to put the drug into the cup which
was to be offered to Gabrielle Tennison, and which apparently was
placed by mistake before the mystery-man himself. Or else the changing
of the cups was to allay any suspicion that might arise in the mind of
the other victim, which was perhaps most likely.

According to Gabrielle, it seemed that at the moment of her seizure
Horton re-entered the room and said some words in a low tone to his
master, whereupon the latter rose, left the table, and evidently went
to greet me, leaving Gabrielle in Miss Engledue's care.

Horton, even though he had been engaged in serving the dinner at the
rear of the house, was apparently also on the look-out for me, and now
I recollected that on my journey down from York, I had mentioned to
Suzor my habit of going to visit my uncle in Orchard Street on certain
evenings. He had asked me to dine with him on the seventh, but I had
excused myself as my uncle would expect me that evening. He evidently
held previous knowledge that the route I habitually took was through
Stretton Street, hence the plot to get me within that house. Besides,
it was quite likely that Suzor himself was watching for me and had
sent Horton out to call me. In any case, the plot had been well-timed
and elaborately thought out.

The fact was plain that Gabrielle Engledue, who had sent her luggage
to the station cloak-room and was about to return to Madrid, was
killed, probably by the scratch of a pin upon which orosin had been
placed.

"All this is most astounding," declared Superintendent Fletcher. "Of
course, De Gex contrived that no inquiry would be made concerning the
dead girl. He might have shown you the body of Miss Engledue, but he
had some motive in keeping it from you, and obtaining a death
certificate for the girl who was still living."

"The motive was that he was not quite certain whether the orosin could
be detected. Since then he has grown bolder, as witness the murder of
the Baron van Veltrup," I replied.

"But why should he not have shown you the