"That's our second line of defence, son," he said, "in case anything goes wrong. I don't mean to minimize the risks. There's very, very nimble-minded people working against us, and the trouble is that we don't have a ghost of an idea what they're doin'. It's just possible they've laid some kind of trap. Out somewhere there're three people whose ideas or motives we don't know. First, there's Paul Hogenauer. Second, there's that apparently harmless professor of physics, Dr. Albert Keppel. Third, there's the elusive L. It may be that none of 'em has a dangerous purpose at all. Or, again, it's just possible that Hogenauer has laid some sort of trap for us — or whatever agent we send. It's just possible his goin' away to Bristol to-night is a blind. I don't say it's probable, but it's possible."
"And I may walk into this trap?"
H.M. grunted. "That's why I asked you to come here. There's plenty of smart lads who could do a neater job of jemmying a window or cavortin' on a drain-pipe, if that's all I wanted. But you met Hogenauer in the old days. You met him in the character of Robert Butler, a spy and a bitter enemy of England, and Hogenauer never forgets a face. So far as we know, he never knew any different about you. If by any chance this is a trap, you'll walk into it before you've done any damage. You can pretend to be an ally of his, you can pretend to be on his side — and you're the only one who can pretend that. You can get out of it before you're into it, if it is a trap. And you may be able to learn something."
"Or walk into a bullet," I said. "Hogenauer seems to know a whole lot about us. Has it occurred to you that he may know all about me as well, and that he knew about me in my `Butler role?"
"Uh-huh," said H.M., nodding rather vaguely. "Sure, Ken; it was the first thing I thought of. But somehow… I move in mysterious ways of cussedness. You may have noticed it. I got plans at the back of my head; I see a move and jump or two on funny gambits, as Charters can tell you; oh, yes. And somehow I don't think you're in as much danger as you might be. I know I seem to be askin' an awful lot of you, especially at a time like this; and you'd be quite right to tell me to go and jump in the bay. But will you trust the old man?"
"Right," I said. "Let's get on with it. When do I start?"
"Good," said Charters quietly. "You'd better have something to eat first. It won't be dark until close on ten o'clock, but you'd better start about nine and reconnoitre the neighbourhood. Sergeant Davis wrote down Hogenauer's address for me somewhere: I think it's `The Larches,' Valley Road, Moreton Abbot. The servant, as I told you, will be going to see a girl and you'll have a clear road. You'll take a car, of course, but I don't need to tell you to park it some distance away from the house. Take Merrivale's car: or mine if you prefer it, unless Serpos has got it out now…."
H.M. seemed mildly disturbed.
"This Serpos, now," he suggested. "That's your secretary, ain't it? Exceedingly limp feller I saw up here last night?"
Charters was sarcastic. "You always were a suspicious beggar, Merrivale. Sinister-sounding foreign name, eh, and the legend of the villainous secretary? Nonsense! Young Serpos is about as meek and mild as they make 'em. I knew his father quite well. Serpos is an Armenian: but educated in England, of course. He worked in a bank in London, but his health wasn't any too good, and I gave him easier work in a healthier climate. Rather amusing chap," Charters admitted grudgingly, "and an expert mimic when you get him started. He'd make money on the halls."