llowed him was one of those that seem to
be at the back of things, and look like the wrong side of the stage
scenery. A colourless, continuous wall ran down one flank of it,
interrupted at intervals by dull-hued and dirt-stained doors, all shut
fast and featureless save for the chalk scribbles of some passing
gamin. The tops of trees, mostly rather depressing evergreens, showed
at intervals over the top of the wall, and beyond them in the grey and
purple gloaming could be seen the back of some long terrace of tall
Parisian houses, really comparatively close, but somehow looking as
inaccessible as a range of marble mountains. On the other side of the
lane ran the high gilt railings of a gloomy park.

Flambeau was looking round him in rather a weird way. "Do you know," he
said, "there is something about this place that--"

"Hullo!" called out the Duke sharply; "that fellow's disappeared.
Vanished, like a blasted fairy!"

"He has a key," explained their clerical friend. "He's only gone into
one of these garden doors," and as he spoke they heard one of the dull
wooden doors close again with a click in front of them.

Flambeau strode up to the door thus shut almost in his face, and stood
in front of it for a moment, biting his black moustache in a fury of
curiosity. Then he threw up his long arms and swung himself aloft like
a monkey and stood on the top of the wall, his enormous figure dark
against the purple sky, like the dark tree-tops.

The Duke looked at the priest. "Dubosc's escape is more elaborate than
we thought," he said; "but I suppose he is escaping from France."

"He is escaping from everywhere," answered Father Brown.

Valognes's eyes brightened, but his voice sank. "Do you mean suicide?"
he asked.

"You will not find his body," replied the other.

A kind of cry came from Flambeau on the wall above. "My God," he
exclaimed in French, "I know what this place is now! Why, it's the back
of the street where old Hirsch lives. I thought I could recognize the
back of a house as well as the back of a man."

"And Dubosc's gone in there!" cried the Duke, smiting his hip. "Why,
they'll meet after all!" And with sudden Gallic vivacity he hopped up on
the wall beside Flambeau and sat there positively kicking his legs with
excitement. The priest alone remained below, leaning against the wall,
with his back to the whole theatre of events, and looking wistfully
across to the park palings and the twinkling, twilit tre