Indeed, it was in a state of very mixed emotions that I came back into the house after we had walked together as far as the corner of the street.  The mere fact of my having found out for certain that the man with the scar was an agent of McMurtrie’s was enough in itself to give me food for pretty considerable thought.  Any suspicions I may have had as to the genuineness of the doctor’s story were now amply confirmed.  I was not intimately acquainted with the working methods of the High Explosives Trade, but it seemed highly improbable that they could involve the drugging or poisoning of Government officials in public restaurants.  As Tommy had forcibly expressed it, there was some “damned shady work” going on somewhere or other, and for all Sonia’s comforting assurances concerning my own eventual prosperity, I felt that I was mixed up in about as sinister a mystery as even an escaped murderer could very well have dropped into.

The thought of Sonia brought me back to the question of our relations.  I could hardly doubt now that she loved me with all the force of her strange, sullen, passionate nature, and that for my sake she was preparing to take some pretty reckless step.  What this was remained to be seen, but that it amounted to a practical betrayal of her father and McMurtrie seemed fairly obvious from the way in which she had spoken.  From the point of view of my own interests, it was an amazing stroke of luck that she should have fallen in love with me, and yet somehow or other I felt distinctly uncomfortable about it.  I seemed to be taking an unfair advantage of her, though how on earth I was to avoid doing so was a question which I was quite unable to solve.  I certainly couldn’t afford to quarrel with her, and she was hardly the sort of girl to accept anything in the nature of a disappointment to her affections in exactly a philosophic frame of mind.

I was still pondering over this rather delicate problem, when there came a knock at the door, and in answer to my summons Gertie ’Uggins inserted her head.

“The lidy’s gorn?” she observed, looking inquiringly round the room.

I nodded.  “There is no deception, Gertrude,” I said.  “You can search the coal-scuttle if you like.”

She wriggled the rest of her body in round the doorway.  “Mrs. Oldbury sent me up to ask if you’d be wantin’ dinner.”

“No,” I said; “I am going out.”

Gertie nodded thoughtfully.  “Taikin’ ’er, I s’pose?”

“To be quite exact,” I said, “I am dining with another lady.”

There was a short pause.  Then, with an air of some embarrassment Gertie broke the silence. ’"Ere,” she said:  “you know that five bob you give me?”

“Yes,” I said.

“Well, I ain’t spendin’ it on no dinner—­see.  I’m goin’ to buy a ’at wiv it—­a ’at like ’ers:  d’yer mind?”

“I do mind,” I said severely.  “That money was intended for your inside, Gertie, not your outside.  You have your dinner, and I’ll buy you a new hat myself.”