im at the
house in Kremlin Road that evening, gave it to his landlord with
directions to take a cab to Mark's rooms, and if he could, bring back
an answer, after which he waited patiently for his messenger's return.

Binney returned in the course of an hour or so, having found Mark in,
and brought a note which Caffyn tore open impatiently. 'I have a
friend coming to dinner to-night, Mr. Binney,' he said, turning round
with his pleasant smile when he had read the answer. 'It's Sunday, I
know, but Mrs. Binney won't mind for once, and tell her she must do
her very best; I want to give my friend a little surprise.'

CHAPTER XXIII.

PIANO PRACTICE.

Caffyn was conscious of a certain excitement that Sunday evening as he
waited for Mark Ashburn's arrival. He felt that he might be standing
on the threshold of a chamber containing the secret of the other's
life--the key of which that very evening might deliver into his hands.
He was too cautious to jump at hasty conclusions; he wished before
deciding upon any plan of action to be practically certain of his
facts; a little skilful manipulation, however, would most probably
settle the question one way or the other, and if the result verified
his suspicions he thought he would know how to make use of his
advantage. There is a passage in the 'Autocrat of the Breakfast Table'
where the author, in talking of the key to the side-door by which
every person's feelings may be entered, goes on to say, 'If nature or
accident has put one of these keys into the hands of a person who has
the torturing instinct, I can only solemnly pronounce the words that
justice utters over its doomed victims, "The Lord have mercy on your
soul!"' There, it is true, the key in question unlocks the delicate
instrument of the nervous system, and not necessarily a Bluebeard's
chamber of guilt; but where the latter is also the case to some extent
the remark by no means loses in significance, and if any man had the
torturing instinct to perfection, Caffyn might be said to be that
individual. There was nothing he would enjoy more than practising upon
a human piano and putting it hopelessly out of tune; but pleasant as
this was, he felt he might have to exercise some self-denial here, at
all events for the present, lest his instrument should become restive
and escape before he had quite made up his mind what air he could best
play upon it.

In the meantime Mark was preparing to keep the appointment in t