point out any mistake in it. But it
wasn't written by Hirsch. If he's a French patriot he didn't write it,
because it gives information to Germany. And if he's a German spy he
didn't write it, well--because it doesn't give information to Germany."

"You mean the information is wrong?" asked Father Brown.

"Wrong," replied the other, "and wrong exactly where Dr Hirsch would
have been right--about the hiding-place of his own secret formula in his
own official department. By favour of Hirsch and the authorities, the
Duke and I have actually been allowed to inspect the secret drawer at
the War Office where the Hirsch formula is kept. We are the only people
who have ever known it, except the inventor himself and the Minister for
War; but the Minister permitted it to save Hirsch from fighting. After
that we really can't support Dubosc if his revelation is a mare's nest."

"And it is?" asked Father Brown.

"It is," said his friend gloomily. "It is a clumsy forgery by somebody
who knew nothing of the real hiding-place. It says the paper is in the
cupboard on the right of the Secretary's desk. As a fact the cupboard
with the secret drawer is some way to the left of the desk. It says
the grey envelope contains a long document written in red ink. It isn't
written in red ink, but in ordinary black ink. It's manifestly absurd to
say that Hirsch can have made a mistake about a paper that nobody knew
of but himself; or can have tried to help a foreign thief by telling him
to fumble in the wrong drawer. I think we must chuck it up and apologize
to old Carrots."

Father Brown seemed to cogitate; he lifted a little whitebait on his
fork. "You are sure the grey envelope was in the left cupboard?" he
asked.

"Positive," replied Flambeau. "The grey envelope--it was a white
envelope really--was--"

Father Brown put down the small silver fish and the fork and stared
across at his companion. "What?" he asked, in an altered voice.

"Well, what?" repeated Flambeau, eating heartily.

"It was not grey," said the priest. "Flambeau, you frighten me."

"What the deuce are you frightened of?"

"I'm frightened of a white envelope," said the other seriously, "If it
had only just been grey! Hang it all, it might as well have been grey.
But if it was white, the whole business is black. The Doctor has been
dabbling in some of the old brimstone after all."

"But I tell you he couldn't have written such a note!" cried Flambeau.
"The note is utt