“You do not accompany your brother, then?” I ventured.

“No.  I’m staying in Calais, where I have an—­an engagement.”  She smiled plaintively at me.

Mr. Watts came back into the compartment, and, standing on the step, said good-by to his sister, and embraced her.  She kissed him affectionately.  Then, having closed the carriage door, he stolidly resumed his seat, which was on the other side away from the door.  We had the compartment to ourselves.

“A nice girl,” I reflected.

The train whistled, and a porter ran along to put the catches on all the doors.

“Good-by; we’re off,” I said to Miss Watts.

“Monsieur,” she said, and her face seemed to flush in the cold morning light,—­“monsieur.”  Was she, then, French, to address me like that?

She made a gesture as if she would say something to me of importance, and I put my head out of the window.

“May I ask you to keep an eye on my brother?” she whispered.

“In what way?” I asked, somewhat astonished.

The train began to move, and she walked to keep level with me.

“Do not let him drink at any of the railway buffets on the journey; he will be met at the Gare du Nord.  He is addicted—­”

“But how can I stop him if he wants to—­”

She had an appealing look, and she was running now to keep pace with the train.

“Ah, do what you can, sir.  I ask it as a favor.  Pardon the request from a perfect stranger.”

I nodded acquiescence, and, waving a farewell to the poor girl, sank back into my seat.  “This is a nice commission!” I thought.

Mr. Watts was no longer in his corner.  Also my jewel-case was gone.

“A deliberate plant!” I exclaimed; and I could not help admiring the cleverness with which it had been carried out.

I rushed into the corridor, and looked through every compartment; but Mr. Watts, whom I was to keep from drunkenness, had utterly departed.  Then I made for the handle of the communication cord.  It had been neatly cut off.  The train was now travelling at a good speed, and the first stop would be Amiens.  I was too ashamed of my simplicity to give the news of my loss to the other passengers in the carriage.

“Very smart indeed!” I murmured, sitting down, and I smiled—­for, after all, I could afford to smile.

CHAPTER XI

A CHAT WITH ROSA

“And when I sat down it was gone, and the precious Mr. Watts had also vanished.”

“Oh!” exclaimed Rosa.  That was all she said.  It is impossible to deny that she was startled, that she was aghast.  I, however, maintained a splendid equanimity.