ff!"

"But--"

"Get!"

"Then I don't see you again?"

"Meet me in half an hour outside our man's place."

"What man?"

"Marie Fauville's accomplice."

"But you don't know--"

"The address? Why, you gave it to me yourself: Boulevard Richard-Wallace,
No. 8. Go! And don't look such a fool."

He made him spin round on his heels, took him by the shoulders, pushed
him to the door, and handed him over, quite flabbergasted, to a footman.

He himself went out a few minutes later, dragging in his wake the
detectives attached to his person, left them posted on sentry duty
outside a block of flats with a double entrance, and took a motor cab
to Neuilly.

He went along the Avenue de Madrid on foot and turned down the Boulevard
Richard-Wallace, opposite the Bois de Boulogne. Mazeroux was waiting for
him in front of a small three-storied house standing at the back of a
courtyard contained within the very high walls of the adjoining property.

"Is this number eight?"

"Yes, Chief, but tell me how--"

"One moment, old chap; give me time to recover my breath."

He gave two or three great gasps.

"Lord, how good it is to be up and doing!" he said. "Upon my word, I was
getting rusty. And what a pleasure to pursue those scoundrels! So you
want me to tell you?"

He passed his arm through the sergeant's.

"Listen, Alexandre, and profit by my words. Remember this: when a person
is choosing initials for his address at a _poste restante_ he doesn't
pick them at random, but always in such a way that the letters convey a
meaning to the person corresponding with him, a meaning which will enable
that other person easily to remember the address."

"And in this case?"

"In this case, Mazeroux, a man like myself, who knows Neuilly and the
neighbourhood of the Bois, is at once struck by those three letters,
'B.R.W,' and especially by the 'W.', a foreign letter, an English letter.
So that in my mind's eye, instantly, as in a flash, I saw the three
letters in their logical place as initials at the head of the words for
which they stand. I saw the 'B' of 'boulevard,' and the 'R' and the
English 'W' of Richard-Wallace. And so I came to the Boulevard
Richard-Wallace, And that, my dear sir, explains the milk in the
cocoanut."

Mazeroux seemed a little doubtful.

"And what do you think, Chief?"

"I think nothing. I am looking about. I am building up a theory on the
first basis that offers a probable theory. And I say to myself .