“What could you say?” I asked.

“I should tell him that it was a friend of mine—­an artist who was going abroad the next day—­who had seen it happen, and that he’d given me the card and asked me to explain.  It’s just possible Latimer would take me into his confidence.  He would either have to do that or else pretend that the whole thing was a joke.”

“I’m quite sure there was no joke about it,” I said.  “Whether the chap with the scar belongs to McMurtrie’s crowd or not, I’m as certain as I am that I’m standing here that he drugged that wine.  He may not have meant to murder Latimer, but it looks uncommon fishy.”

“It looks even fishier than you think,” answered Tommy.  “I’d forgotten for the moment, when you asked about him, but I remember now that some fellow at the Athenians once told me that Latimer was supposed to be a secret-service man of some kind.”

“A secret-service man!” I repeated incredulously.  “I didn’t know we went in for such luxuries in this country except in novels.  Do you believe it?”

“I didn’t pay much attention at the time—­I thought it was probably all rot—­but this business—­” He stopped, and thrusting his hands into his pockets, again paced slowly up and down the room.

I gave a thoughtful whistle.  “By Jove, Tommy!” I said; “if that’s a fact and the gentleman with the scar is really one of our crowd, I seem to have dropped in for a rather promising time—­don’t I!  I knew I was up against the police, but it’s a sort of cheerful surprise to find that I’m taking on the secret service as well.”

Tommy pulled up short.  “Look here, Neil!” he said.  “I don’t like it; I’m hanged if I do.  There’s some rotten dirty work going on somewhere; that’s as plain as a pikestaff.  I believe these people are simply using you as a cats-paw.  All they want is to get hold of the secret of this new explosive of yours; then as likely as not they’ll hand you over to the police, or else....” he paused.  “Well, you’ve seen the sort of crowd they are.  It may be all rot about Latimer being in the secret service, but there’s no doubt they tried to poison or drug him last night.  Men who will go as far as that wouldn’t stick at getting rid of you if it happened to suit their book.”

I nodded.  “That’s all true enough, Tommy,” I said; “but what am I to do?  I took the bargain on, and I’ve no choice now except to go through with it.  I can’t walk up to a policeman and say I think Dr. McMurtrie is a dangerous person engaged on some sort of illegal enterprise.”

Tommy came up, and laid his hand on my shoulder.  “Drop it, Neil; chuck the whole thing and go to America.  Joyce has got that eight hundred pounds of yours; and I can easily let you have another two or three.  In six months’ time you’ll be able to make as much money as you choose.  You’ve had three years of hell; what’s the good of running any risks that you can avoid?  If there’s the least faintest chance of getting