“But his attack on us at Montpellier, and later on you here, coming at about the same time as their visit—­”

“Coincidence, if you ask me.  The weight of probability is against any collusion between the two parties.”

“Please explain...”

“Dupont is an Apache of Paris.  The language he used to me when we fought in that carriage at Montpellier was the slang of the lowest order of Parisian criminal, used spontaneously, under stress of great excitement, with no intent to mislead.  These other people were—­if anything but poor misjudged lambs—­swell mobsmen, the elite of the criminal world.  The two castes never work together because they can’t trust each other.  The swell mobsman works with his head and only kills when cornered.  The Apache kills first, as a matter of instinct, and then thinks—­to the best of his ability.  The Apache knows the swell mobsman can outwit him.  The swell mobsman knows the Apache will assassinate him at the first hint of a suspicion of his good faith.  So they rarely if ever make use of each other.”

“You say ‘rarely.’  But possibly in this instance?”

“I think not.  Dupont was employed as your chauffeur, you’ve told me, upwards of a month.  He had ample opportunity to familiarise himself with the premises and pass the information on, if acting in connivance with those others.  But we know he didn’t, or they would never have shown themselves here in order to secure information they couldn’t have got otherwise.”

“I see, monsieur,” said the woman.  “Then you think the thief may have been any one of the Monk party—­”

“Or several of them acting in concert,” Lanyard interrupted, smiling.

“Or Albert.”

“Not Dupont.  Unless I underestimate him gravely he is incapable of such finesse.  He is a thug first, a thief afterwards.  He would have killed me out of hand if it had been he who had me at his mercy, down here, in the dark.  Nor would he have been able to open the safe without using an explosive.  That, indeed, is why, as I understand him, Dupont attacked you at Montpellier.  If he could have disposed of you there, he would have returned here to work upon the safe and blow it at his leisure, fobbing the servants off with some yarn, or if they proved too troublesome intimidating them, killing one or two if necessary.”

“But why has he made no other attempt—?”

“You forget the police have been making the neighbourhood fairly warm for him.  Besides, he wanted me out of the way before he tried housebreaking.  If he had succeeded in murdering me that night, I don’t doubt he would have burglarised the chateau soon after.  But he failed; the police were stirred up to renewed activity; and if Monsieur Dupont is not now safely back in Paris, hiding in some warren of Montmartre or Belleville, I am much mistaken in the man—­a type I know well.”

“Eliminating Albert then—­”

“There remains the Monk lot.”