At this moment the conductor appeared upon the scene, and began to expostulate loudly.

“Here, I say, what’s all this?  It can’t be allowed.  No fighting and quarrelling are permitted.”

“Well, then, people must behave themselves,” I retorted.  “Don’t let this chap annoy your passengers.”

“I have done nothing to annoy them,” stammered the other.  “You shall answer for this.  I’ve done no harm.”

“I’ll see you don’t.  Get in there and stay there;” and with that I forced him, almost flung him, into his compartment, where he fell panting upon the velvet sofa.

“You’d better keep an eye on him,” I said to the conductor, who was inclined to be disagreeable, and was barely pacified by a couple of five-franc pieces.  “Fellows of this sort are apt to be a nuisance, and we must take care of the ladies.”

As I said this I saw Mrs. Blair’s face peering out beyond her door a little nervously, but she ventured to come right out and along the passage towards me.

“What has happened?  I heard some noise, high words, a scuffle.”

“Some ruffian who got in at Amiens, and who has had to be taught manners.  I told him not to smoke here, and he wanted to intrude himself upon you, which I prevented, a little forcibly.”

“Where is he?  In here?” and she followed the indication of my thumb as I jerked it back, and looked over my shoulder into the compartment.

“Ah!” The ejaculation was involuntary, and one of acute painful surprise, the gesture that accompanied it spontaneous and full of terror.

“That man! that man!” she gasped.  “He must not see me; let me go, let me go!”

But her strength failed her, and but for my supporting arm she would have fallen to the ground.  Half-fainting, I led her back to her own compartment, where her maid received her tenderly and with comforting words.  There was clearly a strong bond of affection between these two, possibly companions and confederates in wrong-doing; the delicate and refined woman, tormented by the inner qualms of outraged conscience, relied and leant upon the stronger and more resolute nature.

“What’s come to you, ma’am?  There, there, don’t give way,” said the maid, softly coaxing her and stroking her hands.

“Oh, Philpotts, fancy!  He is there!  Falfani, the—­the—­you know—­”

Of course I saw it all now.  Stupid ass!  I might have guessed it all along.  I had puzzled my brains vainly trying to place him, to fix his quality and condition in life, neglecting the one simple obvious solution to which so many plain indications pointed.  The man, of course, was a detective, an officer or private agent, and his dirty business—­you see, I was already shaken in my honesty, and now with increasing demoralization under seductive influences I was already inclined to cross over to the other side of the frontier of crime—­his dirty business was the persecution of my sweet friend.