A faint smile touched Dunn's lips. The situation seemed not to be
without a grim humour, for if one-half of what he suspected were true,
one might as sensibly and safely attempt to break into the condemned
cell at Pentonville Gaol as into this quiet house.

But then, was it perhaps possible that this fellow, working away so
unconcernedly, within arm's-length of him, was in reality one of them,
seeking to obtain admittance in this way for some reason of his own,
some private treachery, it might be, or some dispute? To Dunn that
did not seem likely. More probably the fellow was merely an
ordinary burglar--some local practitioner of the housebreaking art,
perhaps--whose ill-fortune it was to have hit upon this house to rob
without his having the least idea of the nature of the place he was
trying to enter.

"He might prove a useful recruit for them, though," Dunn thought, and a
sudden idea flashed into his mind, vivid and startling.

For one moment he thought intently, weighing in his mind this idea that
had come to him so suddenly. He was not blind to the risks it involved,
but his eager temperament always inclined him to the most direct and
often to the most dangerous course. His mind was made up, his plan of
action decided.

The scratching of the burglar's tool upon the glass ceased. Already he
had smeared treacle over the square of glass he intended to remove and
had covered it with paper so as to be able to take it out easily and in
one piece without the risk of falling fragments betraying him.

Through the gap thus made he thrust his arm and made sure there were no
alarms fitted and no obstacles in the way of his easy entrance.

Cautiously he unfastened the window and cautiously and silently lifted
the sash, and when he had done so he paused and listened for a space to
make sure no one was stirring and that no alarm had been caused within
the house.

Still very cautiously and with the utmost precaution to avoid making
even the least noise, he put one knee upon the window-sill, preparatory
to climbing in, and as he did so Dunn touched him lightly on the
shoulder.

"Well, my man, what are you up to?" he said softly. And without a
word, without giving the least warning, the burglar, a man evidently
of determination and resource, swung round and aimed at Dunn's head a
tremendous blow with the heavy iron jemmy he held in his right hand.

But Dunn was not unprepared for an attack and those bright, keen eyes of