ority.

"Then I wonder what that is?" said the priest, and stared at the ground
blankly like a fish.

The others all looked down also; and Flambeau used a fierce exclamation
and a French gesture. For it was unquestionably true that down the
middle of the entrance guarded by the man in gold lace, actually between
the arrogant, stretched legs of that colossus, ran a stringy pattern of
grey footprints stamped upon the white snow.

"God!" cried Angus involuntarily, "the Invisible Man!"

Without another word he turned and dashed up the stairs, with Flambeau
following; but Father Brown still stood looking about him in the
snow-clad street as if he had lost interest in his query.

Flambeau was plainly in a mood to break down the door with his big
shoulders; but the Scotchman, with more reason, if less intuition,
fumbled about on the frame of the door till he found the invisible
button; and the door swung slowly open.

It showed substantially the same serried interior; the hall had grown
darker, though it was still struck here and there with the last crimson
shafts of sunset, and one or two of the headless machines had been moved
from their places for this or that purpose, and stood here and there
about the twilit place. The green and red of their coats were all
darkened in the dusk; and their likeness to human shapes slightly
increased by their very shapelessness. But in the middle of them all,
exactly where the paper with the red ink had lain, there lay something
that looked like red ink spilt out of its bottle. But it was not red
ink.

With a French combination of reason and violence Flambeau simply said
"Murder!" and, plunging into the flat, had explored, every corner and
cupboard of it in five minutes. But if he expected to find a corpse he
found none. Isidore Smythe was not in the place, either dead or alive.
After the most tearing search the two men met each other in the outer
hall, with streaming faces and staring eyes. "My friend," said Flambeau,
talking French in his excitement, "not only is your murderer invisible,
but he makes invisible also the murdered man."

Angus looked round at the dim room full of dummies, and in some Celtic
corner of his Scotch soul a shudder started. One of the life-size dolls
stood immediately overshadowing the blood stain, summoned, perhaps,
by the slain man an instant before he fell. One of the high-shouldered
hooks that served the thing for arms, was a little lifted, and Angus h