ard and hair towered
above him. This was the more noticeable because Royce walked always
with a sort of powerful stoop, and seemed to be going about his small
clerical and domestic duties in a heavy and humbled style, like a
buffalo drawing a go-cart.

He raised his head with unusual pleasure at the sight of the priest, and
took him a few paces apart. Meanwhile Merton was addressing the
older detective respectfully indeed, but not without a certain boyish
impatience.

"Well, Mr. Gilder, have you got much farther with the mystery?"

"There is no mystery," replied Gilder, as he looked under dreamy eyelids
at the rooks.

"Well, there is for me, at any rate," said Merton, smiling.

"It is simple enough, my boy," observed the senior investigator,
stroking his grey, pointed beard. "Three minutes after you'd gone for
Mr. Royce's parson the whole thing came out. You know that pasty-faced
servant in the black gloves who stopped the train?"

"I should know him anywhere. Somehow he rather gave me the creeps."

"Well," drawled Gilder, "when the train had gone on again, that man had
gone too. Rather a cool criminal, don't you think, to escape by the very
train that went off for the police?"

"You're pretty sure, I suppose," remarked the young man, "that he really
did kill his master?"

"Yes, my son, I'm pretty sure," replied Gilder drily, "for the trifling
reason that he has gone off with twenty thousand pounds in papers that
were in his master's desk. No, the only thing worth calling a difficulty
is how he killed him. The skull seems broken as with some big weapon,
but there's no weapon at all lying about, and the murderer would have
found it awkward to carry it away, unless the weapon was too small to be
noticed."

"Perhaps the weapon was too big to be noticed," said the priest, with an
odd little giggle.

Gilder looked round at this wild remark, and rather sternly asked Brown
what he meant.

"Silly way of putting it, I know," said Father Brown apologetically.
"Sounds like a fairy tale. But poor Armstrong was killed with a giant's
club, a great green club, too big to be seen, and which we call the
earth. He was broken against this green bank we are standing on."

"How do you mean?" asked the detective quickly.

Father Brown turned his moon face up to the narrow facade of the house
and blinked hopelessly up. Following his eyes, they saw that right at
the top of this otherwise blind back quarter of the building, an