ly slim gentleman,
who walked across the bedroom to the bathroom with no more pugnacious
purpose than that of washing himself. He bent over a basin, dried his
dripping hands and face on a towel, and turned again so that the strong
light fell on his face. His brown complexion had gone, his big black
moustache had gone; he--was clean-shaven and very pate. Nothing remained
of the Colonel but his bright, hawk-like, brown eyes. Under the wall
Father Brown was going on in heavy meditation, as if to himself.

"It is all just like what I was saying to Flambeau. These opposites
won't do. They don't work. They don't fight. If it's white instead of
black, and solid instead of liquid, and so on all along the line--then
there's something wrong, Monsieur, there's something wrong. One of these
men is fair and the other dark, one stout and the other slim, one strong
and the other weak. One has a moustache and no beard, so you can't see
his mouth; the other has a beard and no moustache, so you can't see his
chin. One has hair cropped to his skull, but a scarf to hide his neck;
the other has low shirt-collars, but long hair to bide his skull. It's
all too neat and correct, Monsieur, and there's something wrong. Things
made so opposite are things that cannot quarrel. Wherever the one
sticks out the other sinks in. Like a face and a mask, like a lock and a
key..."

Flambeau was peering into the house with a visage as white as a sheet.
The occupant of the room was standing with his back to him, but in front
of a looking-glass, and had already fitted round his face a sort
of framework of rank red hair, hanging disordered from the head and
clinging round the jaws and chin while leaving the mocking mouth
uncovered. Seen thus in the glass the white face looked like the face of
Judas laughing horribly and surrounded by capering flames of hell. For
a spasm Flambeau saw the fierce, red-brown eyes dancing, then they were
covered with a pair of blue spectacles. Slipping on a loose black coat,
the figure vanished towards the front of the house. A few moments later
a roar of popular applause from the street beyond announced that Dr
Hirsch had once more appeared upon the balcony.

FOUR -- The Man in the Passage

TWO men appeared simultaneously at the two ends of a sort of passage
running along the side of the Apollo Theatre in the Adelphi. The evening
daylight in the streets was large and luminous, opalescent and empty.
The passage was co